Implicit declaration of function 'abs' is invalid in C99

Objective-C Programming (2nd Edition) 7. Numbers
1

757×36

To avoid this warning, you should explicitly declare the function abs for usage.

[code]#include <stdio.h>

int abs(int someInteger);

int main(int argc, const char * argv)
{
…
printf(“The abs val of -5 is %d\n”, abs(5));

return 0;

}
[/code]

2

try:

#include <stdlib.h>

Mitch

3

Or you know, do what the book does and include:

You need that one in order for abs() to work.

From the book: “Both functions are declared in stdlib.h:”