C中字符串操作函数strstr strchr

//----------------------------------------------------

//AUTHOR: lanyang123456

//DATE: 2014-11-05

//---------------------------------------------------

/*
str1.c

strstr(haystact, needl)

返回needl第一次在haystack出现的位置；
如果没找到，返回NULL;



test_macro???
*/
#include <string.h>
#include <stdio.h>

int main()
{
const char srcstr[] = "com from china city beijing";
const char str1[] = "china";
const char str2[] = "ok";

const char *retPointer = NULL;

retPointer = strstr(srcstr, str1);
if (retPointer == NULL)
{
printf("Not find the string %s.\n", str1);
}
else
{
printf("We find it and is: %s\n", retPointer);
}

retPointer = strstr(srcstr, str2);
if (retPointer == NULL)
{
printf("Not find the string %s.\n", str2);
}
else
{
printf("We find it and is: %s\n", retPointer);
}

return 0;

}

$ gcc -o str1 str1.c
$ ./str1
We find it and is: china city beijing
Not find the string ok.

/*
str3.c

       char *strchr(const char *s, int c);
返回c在s中第一次出现的位置；若未找到，返回NULL；

       char *strrchr(const char *s, int c);
返回c在s中最后一次出现的位置；若未找到，返回NULL；
*/
#include <string.h>
#include <stdio.h>

int main()
{
const char srcstr[] = "com from china city beijing";
const char chr1 = 'c';
const char chr2 = 'i';

const char *retPointer = NULL;

retPointer = strchr(srcstr, chr1);
if (retPointer == NULL)
{
printf("Not find the char %c.\n", chr1);
}
else
{
printf("We find it and is: %s\n", retPointer);
}

retPointer = strrchr(srcstr, chr2);
if (retPointer == NULL)
{
printf("Not find the char %c.\n", chr2);
}
else
{
printf("We find it and is: %s\n", retPointer);
}

return 0;

}

$ gcc -o str3 str3.c
$ ./str3
We find it and is: com from china city beijing
We find it and is: ing

参考man page