4- C語言常見錯誤

book@100ask:~/C_coding$ gcc -o hello hello.c
book@100ask:~/C_coding$ ./hello
Hello,World 10!
book@100ask:~/C_coding$ cat hello.c
#include<stdio.h>
#include "abc.h"

int main(int argc, char **argv)
{
	int a = ABC;
	if(argc >= 2)
		printf("Hello, %s!\n",argv[1]);
	else
		printf("Hello,World %d!\n",a);
	return 0;
}
book@100ask:~/C_coding$ cat abc.h
#define ABC 10

標頭檔案，雙引號預設會從當前目錄取檔案。如果變成尖括號，則從系統指定目錄去找，而不是當前目錄。

book@100ask:~/C_coding$ sudo vim hello.c
book@100ask:~/C_coding$ gcc -o hello hello.c
hello.c:2:10: fatal error: abc.h: No such file or directory
 #include <abc.h>
          ^~~~~~~
compilation terminated.
bo