strstr(str1,str2) 函数与sscanf()函数功能详解

 strstr(str1,str2) 函数用于判断字符串str2是否是str1的子串。如果是，则该函数返回str2在str1中首次出现的地址；否则，返回NULL。
strstr(str1,str2)返回的是str2在str1中首次出现的地址，也就是说，strstr(str1,str2)返回值能随str1变化而变化，因为他们内容有共用地址，地址一样，输出的内容也一样。因而，在使用或者处理strstr(str1,str2)返回值之前，切记不要对str1字符串进行更改，若要更改，应该等使用完返回值后再更改！！！ 

#include 
#include 
#include 
int main(int argc, char **argv)
{
	char str2[10]= "cdef"; 
	char str1[10]= "abcdefgh"; 
    printf("%s",strstr(str1,str2));
    printf("\n");
    //返回：cdefgh 
    char str3[10] = "cxef"; 
    printf("%s",strstr(str1,str3));
    printf("\n");
    //返回：(null) 
    return 0;
}

如何使用sscanf分析字符串：

#include 
#include 
#include 
static void sscanf_test(void);
static void sscanf_test(void)
{
    int ret;
    char *string;
    int  digit;
    char buf1[255];
    char buf2[255];
    char buf3[255];
    char buf4[255];

    /*1.最简单的用法*/
    string = "china beijing 123";
    ret = sscanf(string, "%s %s %d", buf1, buf2, &digit);
    printf("1.string=%s\n", string);
    printf("1.ret=%d, buf1=%s, buf2=%s, digit=%d\n\n", ret, buf1, buf2, digit);
    /*
    **执行结果:
    **1.string=china beijing 123
    **1.ret=3, buf1=china, buf2=beijing, digit=123
    **可以看出,sscanf的返回值是读取的参数个数
    */

    /*2.取指定长度的字符串*/
    string = "123456789";
    sscanf(string, "%5s", buf1);
    printf("2.string=%s\n", string);
    printf("2.buf1=%s\n\n", buf1);
    /*
    **执行结果:
    **2.string=123456789
    **2.buf1=12345
    */

    /*3.取到指定字符为止的字符串*/
    string = "123/456";
    sscanf(string, "%[^/]", buf1);
    printf("3.string=%s\n", string);
    printf("3.buf1=%s\n\n", buf1);
    /*
    **执行结果:
    **3.string=123/456
    **3.buf1=123
    */

    /*4.取到指定字符集为止的字符串*/
    string = "123abcABC";
    sscanf(string, "%[^A-Z]", buf1);
    printf("4.string=%s\n", string);
    printf("4.buf1=%s\n\n", buf1);
    /*
    **执行结果:
    **4.string=123abcABC
    **4.buf1=123abc
    */

    /*5.取仅包含指定字符集的字符串*/
    string = "0123abcABC";
    sscanf(string, "%[0-9]%[a-z]%[A-Z]", buf1, buf2, buf3);
    printf("5.string=%s\n", string);
    printf("5.buf1=%s, buf2=%s, buf3=%s\n\n", buf1, buf2, buf3);
    /*
    **执行结果:
    **5.string=0123abcABC
    **5.buf1=0123, buf2=abc, buf3=ABC
    */

    /*6.获取指定字符中间的字符串*/
    string = "ioswp7";
    sscanf(string, "%*[^<]<%[^>]", buf1);
    printf("6.string=%s\n", string);
    printf("6.buf1=%s\n\n", buf1);
    /*
    **执行结果:
    **6.string=ioswp7
    **6.buf1=android
    */

    /*7.指定要跳过的字符串*/
    string = "iosVSandroid";
    sscanf(string, "%[a-z]VS%[a-z]", buf1, buf2);
    printf("7.string=%s\n", string);
    printf("7.buf1=%s, buf2=%s\n\n", buf1, buf2);
    /*
    **执行结果:
    **7.string=iosVSandroid
    **7.buf1=ios, buf2=android
    */

    /*8.分割以某字符隔开的字符串*/
    string = "android-iphone-wp7";
    /*
    **字符串取道'-'为止,后面还需要跟着分隔符'-',
    **起到过滤作用,有点类似于第7点
    */
    sscanf(string, "%[^-]-%[^-]-%[^-]", buf1, buf2, buf3);
    printf("8.string=%s\n", string);
    printf("8.buf1=%s, buf2=%s, buf3=%s\n\n", buf1, buf2, buf3);
    /*
    **执行结果:
    **8.string=android-iphone-wp7
    **8.buf1=android, buf2=iphone, buf3=wp7
    */

    /*9.提取邮箱地址*/
    string = "Email:[email protected]";
    sscanf(string, "%[^:]:%[^@]@%[^.].%s", buf1, buf2, buf3, buf4);
    printf("9.string=%s\n", string);
    printf("9.buf1=%s, buf2=%s, buf3=%s, buf4=%s\n\n", buf1, buf2, buf3, buf4);
    /*
    **执行结果:
    **9.string=Email:[email protected]
    **9.buf1=Email, buf2=beijing, buf3=sina, buf4=com.cn
    */

    /*10.过滤掉不想截取或不需要的字符串--补充,
    **在%号后面加一*号,代表过滤这个字符串,不读取
    */
    string = "android iphone wp7";
    sscanf(string, "%s %*s %s", buf1, buf2);
    printf("10.string=%s\n", string);
    printf("10.buf1=%s, buf2=%s\n\n", buf1, buf2);
    /*
    **执行结果:
    **10.string=android iphone wp7
    **10.buf1=android, buf2=wp7
    */
}
int main(int argc, char **argv)
{
    sscanf_test();
    return 0;
}