Thread: Beginner's C, problems with double, float

Firstly, don't use %d, the 'd' modifier is for integers. Use %f for floats & doubles.

http://www.cplusplus.com/reference/c...io/printf.html

Also, be explicit - eg int main(), main also has to return a value see the FAQ.

Code:

#include <stdio.h>

int main(void)
{
    float alpha = 0.9f;
    printf("alpha = %f", alpha);
    
    return 0;
}

Never mind, practice makes perfect - we all had to start somewhere. If you're serious about learning C, get a book as it really helps.

Some suggested ones: http://cboard.cprogramming.com/showthread.php?t=74079

> I'm compiling using gcc on Mac OS X
Use the following compiler options, they'll tell you a lot about your code without having to run it.

Code:

$ cat foo.c
#include <stdio.h>
main(){
float alpha=0.9;
printf("alpha=%d\n",alpha);
}
$ gcc -W -Wall -ansi -pedantic -O2 foo.c
foo.c:2: warning: return type defaults to `int'
foo.c: In function `main':
foo.c:4: warning: int format, double arg (arg 2)
foo.c:5: warning: control reaches end of non-void function