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C++ Exercises: Find the number of pairs of integers in a given array of integers whose sum is equal to a specified number

C++ Array: Exercise-27 with Solution

Write a C++ program to find the number of pairs of integers in a given array of integers whose sum is equal to a specified number.

Sample Solution:

C++ Code :

#include <iostream>
using namespace std;
int main()
{
    int array1[] = {1, 5, 7, 5, 8, 9, 11, 12};
    int s1 = sizeof(array1)/sizeof(array1[0]);

    cout << "Original array: ";
    
    for (int i=0; i < s1; i++) 
    cout << array1[i] <<" ";
    
    int i, sum = 12, ctr = 0;
    cout <<"\nArray pairs whose sum equal to 12: ";
    
    for (int i=0; i<s1; i++)
        for (int j=i+1; j<s1; j++)
            if (array1[i]+array1[j] == sum)
              {
                cout << "\n" << array1[i] << "," << array1[j];
                ctr++;
              }
 
    cout <<"\nNumber of pairs whose sum equal to 12: ";
    cout << ctr;
    
    return 0; 
}

Sample Output:

Original array: 1 5 7 5 8 9 11 12 
Array pairs whose sum equal to 12: 
1,11
5,7
7,5
Number of pairs whose sum equal to 12: 3

Flowchart:

Flowchart: Find the number of pairs of integers in a given array of integers whose sum is equal to a specified number

C++ Code Editor:

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Next: Write a C++ program to arrange the numbers of a given array in a way that the sum of some numbers equal the largest number in the array.

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C++ Programming: Tips of the Day

Can I assume (bool)true == (int)1 for any C++ compiler?

According to the standard, you should be safe with that assumption. The C++ bool type has two values - true and false with corresponding values 1 and 0.

The thing to watch about for is mixing bool expressions and variables with BOOL expression and variables. The latter is defined as FALSE = 0 and TRUE != FALSE, which quite often in practice means that any value different from 0 is considered TRUE.

A lot of modern compilers will actually issue a warning for any code that implicitly tries to cast from BOOL to bool if the BOOL value is different than 0 or 1

Ref: https://bit.ly/3PWhs5N