﻿ C# : Basic Declarations - Exercises, Practice, Solution

# C# Sharp Basic Declarations and Expressions : Exercises, Practice, Solution

## C# Sharp Basic Exercises [104 exercises with solution]

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1. Write a C# Sharp program to print Hello and your name in a separate line.
Expected Output :
Hello: Alexandra Abramov
Click me to see the solution

2. Write a C# Sharp program to print the sum of two numbers.
Click me to see the solution

3. Write a C# Sharp program to print the result of dividing two numbers.
Click me to see the solution

4. Write a C# Sharp program to print the results of the specified operations.
Test data:

• -1 + 4 * 6
• ( 35+ 5 ) % 7
• 14 + -4 * 6 / 11
• 2 + 15 / 6 * 1 - 7 % 2

Expected Output:
23
5
12
3
Click me to see the solution

5. Write a C# Sharp program to swap two numbers.
Test Data:
Input the First Number : 5
Input the Second Number : 6
Expected Output:
After Swapping :
First Number : 6
Second Number : 5
Click me to see the solution

6. Write a C# Sharp program to print the output of the multiplication of three numbers entered by the user.
Test Data:
Input the first number to multiply: 2
Input the second number to multiply: 3
Input the third number to multiply: 6
Expected Output:
2 x 3 x 6 = 36
Click me to see the solution

7. Write a C# Sharp program to print on screen the output of adding, subtracting, multiplying and dividing two numbers entered by the user.
Test Data:
Input the first number: 25
Input the second number: 4
Expected Output:
25 + 4 = 29
25 - 4 = 21
25 x 4 = 100
25 / 4 = 6
25 mod 4 = 1
Click me to see the solution

8. Write a C# Sharp program that prints the multiplication table of a number as input.
Test Data:
Enter the number: 5
Expected Output:
5 * 0 = 0
5 * 1 = 5
5 * 2 = 10
5 * 3 = 15
....
5 * 10 = 50
Click me to see the solution

9. Write a C# Sharp program that takes four numbers as input to calculate and print the average.
Test Data:
Enter the First number: 10
Enter the Second number: 15
Enter the third number: 20
Enter the four number: 30

Expected Output:
The average of 10 , 15 , 20 , 30 is: 18
Click me to see the solution

10. Write a C# Sharp program that takes three numbers (x,y,z) as input and outputs (x+y).z and x.y + y.z.
Test Data:
Enter first number - 5
Enter second number - 6
Enter third number - 7

Expected Output:
Result of specified numbers 5, 6 and 7, (x+y).z is 77 and x.y + y.z is 72
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11. Write a C# Sharp program that takes an age (for example 20) as input and prints something like "You look older than 20".
Test Data:
Expected Output:
You look older than 25
Click me to see the solution

12. Write a C# program that takes a number as input and displays it four times in a row (separated by blank spaces), and then four times in the next row, with no separation. You should do it twice: Use the console. Write and use {0}.
Test Data:
Enter a digit: 25
Expected Output:
25 25 25 25
25252525
25 25 25 25
25252525
Click me to see the solution

13. Write a C# program that takes a number as input and displays a rectangle of 3 columns wide and 5 rows tall using that digit.
Test Data:
Enter a number: 5
Expected Output:
555
5 5
5 5
5 5
555
Click me to see the solution

14. Write a C# program to convert Celsius degrees to Kelvin and Fahrenheit.
Test Data:
Enter the amount of celsius: 30
Expected Output:
Kelvin = 303
Fahrenheit = 86
Click me to see the solution

15. Write a C# program that removes a specified character from a non-empty string using the index of a character.
Test Data:
w3resource
Sample Output:
wresource
w3resourc
3resource
Click me to see the solution

16. Write a C# program to create a new string from a given string where the first and last characters change their positions.
Test Data:
w3resource
Python
Sample Output:
e3resourcw
nythoP
x
Click me to see the solution

17. Write a C# program to create a string from a given string (length 1 or more) with the first character added at the front and back.
Sample Output:
Input a string : The quick brown fox jumps over the lazy dog.
TThe quick brown fox jumps over the lazy dog.T
Click me to see the solution

18. Write a C# program to check a pair of integers and return true if one is negative and one is positive.
Sample Output:
Input first integer:
-5
Input second integer:
25
Check if one is negative and one is positive:
True
Click me to see the solution

19. Write a C# program to compute the sum of two given integers. If two values are the same, return the triple of their sum.
Click me to see the solution

20. Write a C# program to get the absolute value of the difference between two given numbers. Return double the absolute value of the difference if the first number is greater than the second number.
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21. Write a C# program to check the sum of the two given integers. Return true if one of the integers is 20 or if their sum is 20.
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22. Write a C# program to check if the given integer is within 20 of 100 or 200.
Sample Output:
Input an integer:
25
False
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23. Write a C# program to convert a given string into lowercase.
Sample Output:
write a c# sharp program to display the following pattern using the alphabet.
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24. Write a C# program to find the longest word in a string.
Test Data: Write a C# Sharp Program to display the following pattern using the alphabet.
Sample Output:
following
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25. Write a C# program to print odd numbers from 1 to 99. Prints one number per line.
Sample Output:
Odd numbers from 1 to 99. Prints one number per line.
1
3
5
7
9
...
95
97
99
Click me to see the solution

26. Write a C# program to compute the sum of the first 500 prime numbers.
Sample Output:
Sum of the first 500 prime numbers:
824693
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27. Write a C# program and compute the sum of an integer's digits.
Sample Output:
Input a number(integer): 12
Sum of the digits of the said integer: 3
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28. Write a C# program to reverse the words of a sentence.
Sample Output:
Original String: Display the pattern like pyramid using the alphabet.
Reverse String: alphabet. the using pyramid like pattern the Display
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29. Write a C# program to find the size of a specified file in bytes.
Sample Output:
Size of a file: 31
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30. Write a C# program to convert a hexadecimal number to a decimal number.
Sample Output:
Convert to-
Decimal number: 1200
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31. Write a C# program to multiply the corresponding elements of two integer arrays.
Sample Output:
Array1: [1, 3, -5, 4]
Array2: [1, 4, -5, -2]
Multiply corresponding elements of two arrays:
1 12 25 -8
Click me to see the solution

32. Write a C# program to create a string of four copies, taking the last four characters from a given string. If the given string is less than 4, return the original one.
Sample Output:
Input a string : The quick brown fox jumps over the lazy dog.
dog.dog.dog.dog.
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33. Write a C# program to check if a given positive number is a multiple of 3 or 7.
Sample Output:
Input first integer:
15
True
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34. Write a C# program to check if a string starts with a specified word.
Note: Suppose the sentence starts with "Hello"
Sample Data: string1 = "Hello how are you?"
Result: Hello.
Sample Output:
Input a string : Hello how are you?
True
Click me to see the solution

35. Write a C# program to check two given numbers where one is less than 100 and the other is greater than 200.
Sample Output:
Input a first number(<100): 75
Input a second number(>100): 250
True
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36. Write a C# program to check if an integer (from the two given integers) is in the range -10 to 10.
Sample Output:
Input a first number: -5
Input a second number: 8
True
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37. Write a C# program to check if "HP" appears at the second position in a string and return the string without "HP".
Test Data: PHP Tutorial
Sample Output:
P Tutorial
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38. Write a C# program to get a string of two characters from a given string. The first and second characters of the given string must be "P" and "H", so PHP will be "PH".
Test Data: PHP
Sample Output:
PH
Click me to see the solution

39. Write a C# program to find the largest and lowest values from three integer values.
Test Data:
Input first integer:
15
Input second integer:
25
Input third integer:
30
Sample Output
Largest of three: 30
Lowest of three: 15
Click me to see the solution

40. Write a C# program that checks the nearest value of 20 of two given integers and return 0 if two numbers are same.
Test Data:
Input first integer:
15
Input second integer:
12
Sample Output
15
Click me to see the solution

41. Write a C# program to check if a given string contains the 'w' character between 1 and 3 times.
Test Data:
Input a string (contains at least one 'w' char) : w3resource
Test the string contains 'w' character between 1 and 3 times:
Sample Output
True
Click me to see the solution

42. Write a C# program to create a string where the first 4 characters are in lower case. If the string is less than 4 letters, make the whole string in upper case.
Test Data:
Input a string: w3r
Sample Output
W3R
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43. Write a C# program to check if a given string starts with "w" and is immediately followed by two "ww".
Test Data:
Input a string : www
Sample Output
False
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44. Write a C# program to create a string of every other character (odd position) from the first position of a given string.
Test Data:
Input a string : w3resource
Sample Output
wrsuc
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45. Write a C# program to count a specified number in a given array of integers.
Test Data:
Input an integer: 5
Sample Output
Number of 5 present in the said array: 2
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46. Write a C# program to check if a number appears as the first or last element of an array of integers. The array length is 1 or more.
Test Data:
Input an integer: 25
Sample Output
False
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47. Write a C# program to compute the sum of all the elements of an array of integers.
Test Data:
Array1: [1, 2, 2, 3, 3, 4, 5, 6, 5, 7, 7, 7, 8, 8, 1]
Sample Output
Sum: 69
Click me to see the solution

48. Write a C# program that checks if the first element and the last element of an array of integers are equal. The array length is 1 or more.
Test Data:
Array1: [1, 2, 2, 3, 3, 4, 5, 6, 5, 7, 7, 7, 8, 8, 1]
Sample Output
True
Click me to see the solution

49. Write a C# program to check if the first or the last element of the two arrays (length 1 or more) are equal.
Test Data:
Array1: [1, 2, 2, 3, 3, 4, 5, 6, 5, 7, 7, 7, 8, 8, 1]
Array2: [1, 2, 2, 3, 3, 4, 5, 6, 5, 7, 7, 7, 8, 8, 5]
Check if the first element or the last element of the two arrays ( leng th 1 or more) are equal.
Sample Output
True
Click me to see the solution

50. Write a C# program to rotate an array (length 3) of integers in the left direction.
Test Data:
Array1: [1, 2, 8]
After rotating array becomes: [2, 8, 1]
Click me to see the solution

51. Write a C# program to get the largest value between the first and last element of an array (length 3) of integers.
Test Data:
Array1: [1, 2, 5, 7, 8]
Highest value between first and last values of the said array: 8
Click me to see the solution

52. Write a C# program to create a new array of length containing the middle elements of three arrays (each length 3) of integers.
Test Data:
Array1: [1, 2, 5]
Array2: [0, 3, 8]
Array3: [-1, 0, 2]
New array: [2, 3, 0]
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53. Write a C# program to check if an array contains an odd number.
Test Data:
Original array: [2, 4, 7, 8, 6]
Check if an array contains an odd number? True
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54. Write a C# program to get the century of a year.
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55. Write a C# program to find the pair of adjacent elements that has the largest product of the given array.
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56. Write a C# program to check if a given string is a palindrome or not.
Sample Example:
For 'aaa' the output should be true
For 'abcd' the output should be false
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57. Write a C# program to find the pair of adjacent elements that has the highest product of an array of integers.
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58. Write a C# program that accepts a list of integers and checks how many integers are needed to complete the range.
Sample Example [1, 3, 4, 7, 9], between 1-9 -> 2, 5, 6, 8 are not present in the list. So output will be 4.
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59. Write a C# program to check whether it is possible to create a strictly increasing sequence from a given sequence of integers as an array.
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60. Write a C# program to calculate the sum of all integers in a rectangular matrix. However, exclude those integers located below an integer of value 0.
Sample Example:
matrix = [[0, 2, 3, 2],
[0, 6, 0, 1],
[4, 0, 3, 0]]
Eligible integers which will be participated to calculate the sum -
matrix = [[X, 2, 3, 2],
[X, 6, X, 1],
[X, X, X, X]]
Therefore sum will be: 2 + 3 + 2 + 6 + 1 = 14
Click me to see the solution

61. Write a C# program to sort the integers in ascending order without moving the number -5.
Click me to see the solution

62. Write a C# program to reverse the strings contained in each pair of matching parentheses in a given string. It should also remove the parentheses from the given string.
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63. Write a C# program to check if a given number is present in an array of numbers.
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64. Write a C# Sharp program to get the file name (including extension) from a given path.
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65. Write a C# Sharp program to multiply all elements of a given array of numbers by array length.
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66. Write a C# Sharp program to find the minimum value from two numbers given to you, represented as a string.
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67. Write a C# Sharp program to create a coded string from a given string, using a specified formula.
Replace all 'P' with '9', 'T' with '0', 'S' with '1', 'H' with '6' and 'A' with '8'.
Sample Output:
969
J8V81CRI90
Click me to see the solution

68. Write a C# Sharp program to count a specified character (both cases) in a given string.
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69. Write a C# Sharp program to check if a given string contains only lowercase or uppercase characters.
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70. Write a C# Sharp program to remove the first and last elements from a given string.
Sample Output:
Original string: PHP
After removing first and last elements: H
Original string: Python
After removing first and last elements: ytho
Original string: JavaScript
After removing first and last elements: avaScrip
Click me to see the solution

71. Write a C# Sharp program to check if a given string contains two similar consecutive letters.
Sample Output:
Original string: PHP
Test for consecutive similar letters! False
Original string: PHHP
Test for consecutive similar letters! True
Original string: PHPP
Test for consecutive similar letters! True
Original string: PPHP
Test for consecutive similar letters! True
Click me to see the solution

72. Write a C# Sharp program to check whether the average value of the elements of a given array of numbers is a whole number or not.
Sample Output:
nums = { 1, 2, 3, 5, 4, 2, 3, 4 }
Check the average value of the said array is a whole number or not: True
nums1 = { 2, 4, 2, 6, 4, 8 }
Check the average value of the said array is a whole number or not: False
Click me to see the solution

73. Write a C# Sharp program to convert the letters of a given string (same case-upper/lower) into alphabetical order.
Sample Output:
Original string: PHP
Convert the letters of the said string into alphabetical order: HPP
Original string: javascript
Convert the letters of the said string into alphabetical order: aacijprstv
Original string: python
Convert the letters of the said string into alphabetical order: hnopty
Click me to see the solution

74. Write a C# Sharp program to check the length of a given string is odd or even. Return 'Odd length' if the string length is odd otherwise 'Even length'.
Sample Output:
Original string: PHP
Convert the letters of the said string into alphabetical order: Odd length
Original string: javascript
Convert the letters of the said string into alphabetical order: Even length
Original string: python
Convert the letters of the said string into alphabetical order: Even length
Click me to see the solution

75. Write a C# Sharp program that takes a positive number and returns the nth odd number.
Sample Output:
1st odd number: 1
2nd odd number: 3
4th odd number: 7
100th odd number: 199
Click me to see the solution

76. Write a C# Sharp program to get the ASCII value of a given character.
Sample Output:
Ascii value of 1 is: 49
Ascii value of A is: 65
Ascii value of a is: 97
Ascii value of # is: 35
Click me to see the solution

77. Write a C# Sharp program to check whether a word is plural or not.
Sample Output:
Is 'Exercise' is plural? False
Is 'Exercises' is plural? True
Is 'Books' is plural? True
Is 'Book' is plural? False
Click me to see the solution

78. Write a C# Sharp program to find the sum of squares of elements in a given array of integers.
Sample Output:
Sum of squares of elements of the said array: 14
Sum of squares of elements of the said array: 29
Click me to see the solution

79. Write a C# Sharp program to convert an integer to a string and a string to an integer.
Sample Output:
Original value and type: 50, System.String
Convert string to integer:
Return value and type: 50, System.Int32
Original value and type: 122, System.Int32
Convert integer to string:
Return value and type: 122, System.String
Click me to see the solution

80. Write a C# Sharp program to convert all the values of a given array of mixed values to string values.
Sample Output:
Printing original array elements and their types:
Value-> 25 :: Type-> System.Int32
Value-> Anna :: Type-> System.String
Value-> False :: Type-> System.Boolean
Value-> 4/15/2021 10:37:47 AM :: Type-> System.DateTime
Value-> 112.22 :: Type-> System.Double
Printing array elements and their types:
Value-> 25 :: Type-> System.String
Value-> Anna :: Type-> System.String
Value-> False :: Type-> System.String
Value-> 4/15/2021 10:37:47 AM :: Type-> System.String
Value-> 112.22 :: Type-> System.String
Click me to see the solution

81. Write a C# Sharp program to swap a two-digit number and check whether the given number is greater than its swap value.
Sample Output:
Input an integer value:
Check whether the said value is greater than its swap value: True
Click me to see the solution

82. Write a C# Sharp program to remove all non-letter characters from a given string.
From Wikipedia,
A letter is a segmental symbol of a phonemic writing system. The inventory of all letters forms the alphabet. Letters broadly correspond to phonemes in the spoken form of the language, although there is rarely a consistent, exact correspondence between letters and phonemes
Sample Output:
Orginal string: Py@th12on
Remove all characters from the said string which are non-letters: Python
Orginal string: Python 3.0
Remove all characters from the said string which are non-letters: Python
Orginal string: 2^sdfds*^*^jlljdslfnoswje34u230sdfds984
Remove all characters from the said string which are non-letters: sdfdsjlljdslfnoswjeusdfds
Click me to see the solution

83. Write a C# Sharp program to remove all vowels from a given string.
Sample Output:
Orginal string: Python
After removing all the vowels from the said string: Pythn
Orginal string: C Sharp
After removing all the vowels from the said string: C Shrp
Orginal string: JavaScript
After removing all the vowels from the said string: JvScrpt
Click me to see the solution

84. Write a C# Sharp program to get the index number of all lower case letters in a given string.
Sample Output:
Orginal string: Python
Indices of all lower case letters of the said string:
1 2 3 4 5
Orginal string: JavaScript
Indices of all lower case letters of the said string:
1 2 3 5 6 7 8 9
Click me to see the solution

85. Write a C# Sharp program to find the cumulative sum of an array of numbers.
A cumulative sum is a sequence of partial sums of a given sequence. For example, the cumulative sums of the sequence {x, y, z,...}, are x , x+y , x+y+z
Sample Output:
Orginal Array elements:
1 3 4 5 6 7
Cumulative sum of the said array elements:
1 4 8 13 19 26
Orginal Array elements:
1.2 -3 4.1 6 -5.47
Cumulative sum of the said array elements:
1.2 -1.8 2.3 8.3 2.83
Click me to see the solution

86. Write a C# Sharp program to get the number of letters and digits in a given string.
Sample Output:
Original string:: Python 3.0
Number of letters: 6 Number of digits: 2
Original string:: dsfkaso230samdm2423sa
Number of letters: 14 Number of digits: 7
Click me to see the solution

87. Write a C# Sharp program to reverse a Boolean value.
Sample Output:
Original value: False
Reverse value: True
Original value: True
Reverse value: False
Click me to see the solution

88. Write a C# Sharp program to find the sum of the interior angles (in degrees) of a given polygon. Input the number of straight lines.
From Wikipedia,
In geometry, a polygon is a plane figure that is described by a finite number of straight line segments connected to form a closed polygonal chain or polygonal circuit. The solid plane region, the bounding circuit, or the two together, may be called a Polygon.
Sample Output:
Input number of straight lines of the polygon:
Sum of the interior angles (in degrees) of the said polygon: -360
Click me to see the solution

89. Write a C# Sharp program to count positive and negative numbers in a given array of integers.
Sample Output:
Original Array elements:
10 -11 12 -13 14 -18 19 -20
Number of positive numbers: 4
Number of negative numbers: 4
Original Array elements:
-4 -3 -2 0 3 5 6 2 6
Number of positive numbers: 5
Number of negative numbers: 3
Original Array elements:
Number of positive numbers: 0
Number of negative numbers: 0
Click me to see the solution

90. Write a C# Sharp program to count the number of ones and zeros in the binary representation of a given integer.
Sample Output:
Original number: 12
Number of ones and zeros in the binary representation of the said number:
Number of ones: 2
Number of zeros: 2
Original number: 1234
Number of ones and zeros in the binary representation of the said number:
Number of ones: 5
Number of zeros: 6
Click me to see the solution

91. Write a C# Sharp program to remove all values except integer values from a given array of mixed values.
Sample Output:
Original array elements:
25 Anna False 4/24/2021 11:43:11 AM -112 -34.67
After removing all the values except integer values from the said array of mixed values: 25 -112
Click me to see the solution

92. Write a C# Sharp program to find the next prime number of a given number. If the given number is a prime number, return the number.
From Wikipedia,
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 4 is composite because it is a product (2 × 2) in which both numbers are smaller than 4. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order.
Sample Output:
Original number: 120
Next prime number/Current prime number: 127
Original number: 321
Next prime number/Current prime number: 331
Original number: 43
Next prime number/Current prime number: 43
Original number: 4433
Next prime number/Current prime number: 4441
Click me to see the solution

93. Write a C# Sharp program to calculate the square root of a given number. Return the integer part of the result instead of using any built-in functions.
Sample Data:
(120) -> 10
(225) -> 15
(335) -> 18
Click me to see the solution

94. Write a C# program that finds the longest common prefix from an array of strings.
Sample Data:
({ "Padas", "Packed", "Pace", "Pacha" }) -> "Pa"
({ "Jacket", "Joint", "Junky", "Jet" }) -> "J"
({ "Bort", "Whang", "Yarder", "Zoonic" }) -> ""
Click me to see the solution

95. Write a C# programme to check the said string is valid or not. The input string will be valid when open brackets and closed brackets are same type of brackets.
Or
open brackets will be closed in proper order.
Sample Data:
( "<>") -> True
("<>()[]{}”) -> True
("(<>”) -> False
("[<>()[]{}]”) -> True
Click me to see the solution

96. Write a C# Sharp program to check whether all characters in a string are the same. Return true if all the characters in the string are the same, otherwise false.
Sample Data:
("aaa") -> True
("abcd") -> False
("3333") -> True
("2342342") -> False
Click me to see the solution

97. Write a C# Sharp program to check if a given string (floating point and negative numbers included) is numeric or not. Return True if the string is numeric, otherwise false.
Sample Data:
("123") -> True
("123.33") -> True
("33/33") -> False
("234234d2") -> False
Click me to see the solution

98. Write a C# Sharp program to create and display all prime numbers in strictly descending decimal digit order.
Sample Data:
2, 3, 5, 7, 31, 41, 43, 53, 61, 71, 73, 83, 97, 421, 431.....
Click me to see the solution

99. Write a C# Sharp program to create and display all prime numbers in strict ascending decimal digit order.
Sample Data:
2, 3, 5, 7, 13, 17, 19, 23, 29, 37, 47, 59, 67, 79,
Click me to see the solution

100. Write a C# Sharp program to check the equality comparison (value and type) of two parameters. Return true if they are equal otherwise false.
Sample Data:
("AAA", "BBB") -> False
(true, false) -> False
(true, "true") -> False
(10, 10) -> True
Click me to see the solution

101. Write a C# Sharp program to calculate the value of e.
Note: e is also known as Euler's number and Napier's constant
Sample Data:
e = 2.718281828459050
Click me to see the solution

102. Write a C# Sharp program to create an identity matrix.
Sample Data:
Input a number: 3
1 0 0
0 1 0
0 0 1
Click me to see the solution

103. Write a C# Sharp program to sort characters in a given string (uppercase/lowercase letters and numbers). Return the newly sorted string.
Sample Data:
("AAAbfed231") -> "AAAbdef123"
(" ") -> "Blank string!"
("Python") -> "hnoPty"
("W3resource") -> "ceeorrsuW3"
Click me to see the solution

104. Write a C# Sharp program to compare the equality of three integers and calculate how many integers have the same value.
Sample Data:
(1,2, 3) -> 0
(1,3,3) -> 2
(3,3,3) -> 3
Click me to see the solution

C# Sharp Code Editor:

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