Addition and subtraction of two numbers in C

In this article we will learn different way of addition and subtraction of two numbers using C programming. Actually it is an arithmetic operation of adding or subtracting two number and print their result. For example, if an user gives two integer or float then we have to print the output of their addition and subtraction.

Adding integers in C

// addition and subtraction, adding two integers
#include <stdio.h>
int main (){
    int firstNumber, secondNumber, sum;

    printf("Enter first number : ");
    scanf("%d", &firstNumber);

    printf("Enter second number : ");
    scanf("%d", &secondNumber);

    sum = firstNumber + secondNumber;
    printf("\nSum is = %d\n", sum);
return 0;
}

Output of this addition program

addition and subtraction program in c

Subtracting integer in C

// addition and subtraction, subtracting integer
#include <stdio.h>
int main (){
    int number1, number2, result;

    printf("Enter first number here : ");
    scanf("%d", &number1);

    printf("Enter second number here : ");
    scanf("%d", &number2);

    result = number1 - number2;
    printf("\nResult is = %d\n", result);
return 0;
}

Output of this C subtraction program

addition and subtraction program in c, subtracting integer

Adding floating point numbers in C

// adding floating point number, addition and subtraction program
#include <stdio.h>
int main (){
    float a, b, result;

    printf("Enter first float number here : ");
    scanf("%f", &a);

    printf("Enter second float number here : ");
    scanf("%f", &b);

    result = a + b;
    printf("\nResult is = %.2f\n", result);   // %.2f will print the result with 2 decimal point
return 0;
}

See the output of this program

addition of floating point number

Subtracting floating point numbers in C

// subtracting floating point number, addition and subtraction program
#include <stdio.h>
int main (){
    float x, y, result;

    printf("Enter first float number : ");
    scanf("%f", &x);

    printf("Enter second float number : ");
    scanf("%f", &y);

    result = x - y;
    printf("\nResult is = %.2f\n", result);
return 0;
}

Output of this program

subtraction floating point number in C

Considering fact before addition and subtraction

Here are some of the most common error we make when adding or subtracting in C. The list is given bellow;

  • We should consider the storage capacity for variables. We can not store bigger number than the maximum limit for any variable.
#include <stdio.h>
int main (){
    int x, y, sum;
    printf("Enter the value of x and y : ");
    scanf("%d%d", &x, &y);

    sum = x + y;
    printf("\nSum is = %d\n", sum);

return 0;
}

This program will give the output correctly like we have given bellow;

c addition program example

But, if a use gives any input that will be more than 2,147,483,647, then we will not get the correct result. See the output bellow;

addition and subtraction error in c

Here, 2000000000 + 2000000000 = 4000000000

But we have got wrong output because of storage capacity of integer variable is 4 bytes which can store maximum 2,147,483,647.

  • Adding floating point number with integer will give wrong result.
#include <stdio.h>
int main (){
    int x = 10;
    float y = 12.25;

    int sum1 = x + y;
    printf("\nSum is = %d\n", sum1);    // int can not store float number

    float sum2 = x + y;
    printf("\nSum is = %f\n", sum2);     // correct result

    printf("\nValue of PI = %d\n", 22/7);     // %d can not print float number

return 0;
}

Here we will get wrong result for first and last case. If we use the value of PI is = 22.0/7 or 22/7.0 then we will get correct result. So, here the output will be as following.

c subtraction program example

Print required output for float number

We can control our output when using floating double variables in C. By default, %lf prints six digits after decimal point.  But we can print any number of digits after decimal point using the given method.

// required output for addition and subtraction
#include <stdio.h>
int main (){
    float firstNum = 3.125;
    float secondNum = 2.454;
    float sum = firstNum + secondNum;

    printf("%f\n", sum);      // by default six digit after decimal point
    printf("%.f\n", sum);     // print only integer part
    printf("%.1f\n", sum);     // print 1 digit after decimal point
    printf("%.2f\n", sum);     // print 2 digit after decimal point
    printf("%.3f\n", sum);     // print 3 digit after decimal point
    printf("%.4f\n", sum);     // print 4 digit after decimal point
    printf("%.5f\n", sum);      // print 5 digit after decimal point
return 0;
}

Output :

5.579000
6
5.6
5.58
5.579
5.5790
5.57900

Process returned 0 (0x0)   execution time : 0.026 s
Press any key to continue.

Repeatedly add two numbers in C using loop

#include <stdio.h>
int main(){
    int x, y, result;
    char ch;

    while(1){
    printf("\nEnter two integer to add them : ");
    scanf("%d%d", &x, &y);
    getchar();

    result = x + y;
    printf("\nResult is = %d\n", result);

    printf("\nDo you want to add more (y/n)\n");
    scanf("%c", &ch);

    if(ch == 'y' || ch == 'Y'){
        continue;
    }else{
        printf("\n\nOk, Thanks\n\n");
        break;
    }
  }
return 0;
}

Output :

Enter two integer to add them : 34 53

Result is = 87

Do you want to add more (y/n)
y

Enter two integer to add them : 60 20

Result is = 80

Do you want to add more (y/n)
n


Ok, Thanks


Process returned 0 (0x0)   execution time : 22.940 s
Press any key to continue.

C program to add two numbers using function

#include<stdio.h>

int addition (int a, int b){    // function declaration
int sum = a + b;
return sum;
}

int main(){
    int a, b;
    printf("Enter two integers : ");
    scanf("%d%d", &a, &b);

    int result = addition(a,b);     // calling function
    printf("Result is = %d\n", result);

return 0;
}

Output :

Enter two integers : 10 30
Result is = 40

Process returned 0 (0x0)   execution time : 8.253 s
Press any key to continue.

If you have any doubt about work with function then see our function chapter to learn about C function. Now, what you have to do is try to practice these and implement other method to add or subtract integers or floating point numbers

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