在C中隐式声明函数'getChar'

Question

Some I have this error when I try to compile a program in C.

myfunctions.c:27:2: warning: implicit declaration of function ‘getChar’ [-Wimplicit-function-declaration]

Here is line 27:

while(myChar = getChar() && myChar != '')

I'm calling this in the header:

#include <stdio.h>
#include <unistd.h>

Answer 1

It's spelled getchar , not getChar . C is case sensitive, and pretty much all the standard C functions' names are all lowercase.

As for why it's "implicitly declared" when it doesn't exist...in older versions of C, if a function name isn't known to the compiler, it's assumed to be a function that returns an int . It's almost as if you said int getChar(); . I hear C99 doesn't allow this, but most compilers don't stick to it anyway unless you tell them to.

Answer 2

I don't know why, but GCC compiler (win platform) knows getch() . But if you switch on -pedantic compilation, than this warning occurs.

Solution: use getchar() and everything should work ok.