Thread: Sum of 2 numbers

Hi everyone. I am trying to do a simple program in C which reads two double numbers from the keyboard and displays the sum to the user. Even though the compiling is ok, the program doesn't run as expected. The code is:

Code:

#include <stdio.h>

int main (void)
{

    double num1, num2, sum;

    printf("Type in the first number: ");
    scanf("%f", &num1);
    printf("Type in the second number: ");
    scanf("%f", &num2);

    sum = num1 + num2;

    printf("%f + %f = %f.", num1, num2, sum);

    return 0;

}

What is wrong with this code?

Thanks in advance!

You might also want to include math.h although it's not strictly necessary in this case.

Thank you very much!

Salem, so every time I wanna print a double variable, I need to use %lf instead of %f?

so every time I wanna print a double variable, I need to use %lf instead of %f?

The %lf is only required for scanf() for a double, which extracts the value from the stream, not print it. Unless you are using C99 or compiler specific extensions printf() uses %f for printing both float and double.

Jim

Originally Posted by jimblumberg

The %lf is only required for scanf() for a double, which extracts the value from the stream, not print it. Unless you are using C99 or compiler specific extensions printf() uses %f for printing both float and double.

Jim

I see. I tried using the %f for printing, and it worked, thanks!