C言語文字列操作関数

/*	file name	: sting_func_test.c 
	author		: zhongjun
	description	:sting_func_test demo
	data		:20150701
	time		:PM 22:36
	key(study)	:string operate
	note		: ， ， memory fault
*/

#include <string.h>
#include <stdio.h>

char dst_string[20] = "hard work";
char *src_string = "hello";

int main()
{
	size_t src_str_len = 0;
	size_t dst_str_len = 0;

	//strlen  NULL， 5
	src_str_len = strlen(src_string);
	dst_str_len = strlen(dst_string);
	printf("src_str_len(%d)
",src_str_len);
	printf("dst_str_len(%d)
",dst_str_len);

#ifdef no_len_limit
	{
		//strcpy  NULL copy , hello
		// copy, dst_string 
		printf("dst_string(%s)
",dst_string);
		strcpy(dst_string,src_string);
		printf("dst_string(%s)
",dst_string);

		//strcat  NULL cat
		strcat(dst_string,src_string);
		printf("dst_string(%s)
",dst_string);
	}
#endif	

#ifdef len_limit
	{
		//strncpy copy strlen(src_string) copy NULL
		//strncpy copy len > strlen(src_string) copy NULL, NULL
		printf("dst_string(%s)
",dst_string);
		strncpy(dst_string,src_string,strlen(src_string));
		//strncpy(dst_string,src_string,strlen(src_string)+1);
		printf("dst_string(%s)
",dst_string);

		//strncat strncmp  len limit 
	}
#endif

#ifdef find_char
	{
		//strchr  ，
		//strrchr  
		//strpbrk   group
		char *pos = NULL;

		pos = strchr(dst_string,'r');
		if(pos != NULL)
			printf("pos_strchr(%s)
",pos);

		pos = strrchr(dst_string,'r');
		if(pos != NULL)
			printf("pos_strrchr(%s)
",pos);

		pos = strpbrk(dst_string,"abcde");
		if(pos != NULL)
			printf("pos_strpbrk(%s)
",pos);
	}
	
#endif

#ifdef find_string
	{
		char *pos = NULL;
		
		pos = strstr(dst_string,"rd");
		if(pos != NULL)
			printf("pos_strstr(%s)
",pos);
	}
#endif
	
	return 0;
}