C Exercises: Prints out the prime numbers between 1 and 200

Last update on September 18 2025 12:35:33 (UTC/GMT +8 hours)

Print prime numbers between 1 and 200 in rows of 20

Write a C program that generates 50 random numbers between -0.5 and 0.5 and writes them to the file rand.dat. The first line of ran.dat contains the number of random numbers, while the next 50 lines contain 50 random numbers.

Expected output:
The prime numbers between 1 and 199 are:
2 3 5 7 11 13 17 19 23 29
31 37 41 43 47 53 59 61 67 71
73 79 83 89 97 101 103 107 109 113
127 131 137 139 149 151 157 163 167 173
179 181 191 193 197

Pictorial Presentation:

Sample Solution:

C Code:

#include <stdio.h>
int main() {
    int i, j, flag, ip = 0;

    // Print a message indicating the purpose of the program
    printf("The prime numbers between 1 and 199 are:\n");

    // Loop to check prime numbers from 2 to 198
    for (i = 2; i < 199; i++) {
        flag = 1;

        // Loop to check if i is divisible by any number other than 1 and itself
        for (j = 2; j <= i / 2 && flag == 1; j++) {
            if (i % j == 0) {
                flag = 0;
            }
        }

        // If i is prime, print it
        if (flag == 1) {
            printf("%5d ", i);
            ip++;

            // Print a newline character after every 10 prime numbers
            if (ip % 10 == 0) {
                printf("\n");
            }
        }
    }

    printf("\n");

    return 0;
}

Sample Output:

The prime numbers between 1 and 199 are:
    2     3     5     7    11    13    17    19    23    29 
   31    37    41    43    47    53    59    61    67    71 
   73    79    83    89    97   101   103   107   109   113 
  127   131   137   139   149   151   157   163   167   173 
  179   181   191   193   197 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to print prime numbers between 1 and 300, formatted in a table with a fixed number of columns.
• Write a C program to generate and display prime numbers up to a user-specified limit with custom row length.
• Write a C program to print prime numbers between 1 and 200 in reverse order while maintaining row formatting.
• Write a C program to display prime numbers in a range with each row containing numbers aligned to a fixed width.

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