How to multiply float with integers in C?

c integer operation
Wicelo picture Wicelo · Jun 12, 2013 · Viewed 71.3k times · Source

When I execute this code it returns me 1610612736

void main(){
float a=3.3f;
int b=2;
printf("%d",a*b);
}

Why and how to fix this ?

edit : It's not even a matter of integer and float, if i replace int b=2: by float b=2.0f it return the same silly result

Answer

Carl Norum picture Carl Norum · Jun 12, 2013

The result of the multiplication of a float and an int is a float. Besides that, it will get promoted to double when passing to printf. You need a %a, %e, %f or %g format. The %d format is used to print int types.

Editorial note: The return value of main should be int. Here's a fixed program:

#include <stdio.h>

int main(void)
{
    float a = 3.3f;
    int b = 2;
    printf("%a\n", a * b);
    printf("%e\n", a * b);
    printf("%f\n", a * b);
    printf("%g\n", a * b);
    return 0;
}

and its output:

$ ./example 
0x1.a66666p+2
6.600000e+00
6.600000
6.6

Related questions

How to convert integer to string in C?

I tried this example: /* itoa example */ #include <stdio.h> #include <stdlib.h> int main () { int i; char buffer [33]; printf ("Enter a number: "); scanf ("%d",&i); itoa (i,buffer,10); printf ("decimal: %s\n",buffer); itoa (i,…

Read More
max value of integer

In C, the integer (for 32 bit machine) is 32 bits, and it ranges from -32,768 to +32,767. In Java, the integer(long) is also 32 bits, but ranges from -2,147,483,648 to +2,147,483,647. I do not understand how the range is different in Java, even …

Read More
How to convert an int to string in C?

How do you convert an int (integer) to a string? I'm trying to make a function that converts the data of a struct into a string to save it in a file.

Read More