C语言字符串处理函数大全

1、strtod()

功 能: 将字符串转换为 double 型值

用 法: double strtod(char *str, char **endptr);

程序例:

#include <stdio.h>
#include <stdlib.h>
int main(void) {
char input[80], *endptr;
double value;
printf("Enter a floating point number:");
gets(input);
value = strtod(input, &endptr);
printf("The string is %s the number is %lf\n", input, value);
return 0;
}

2、strtol()

功 能: 将字符串转换为长整数

用 法: long strtol(char *str, char **endptr, int base);

程序例:

#include <stdlib.h>
#include <stdio.h>
int main(void) {
char *string = "87654321", *endptr;
long lnumber;
/* strtol converts string to long integer */
lnumber = strtol(string, &endptr, 10);
printf("string = %s long = %ld\n", string, lnumber);
return 0;
}

3、stpcpy()

功 能: 拷贝一个字符串到另一个

用 法: char *stpcpy(char *destin, char *source);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char string[10];
char *str1 = "abcdefghi";
stpcpy(string, str1);
printf("%s\n", string);
return 0;
}

4、strcat()

功 能: 字符串拼接函数

用 法: char *strcat(char *destin, char *source);

序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char destination[25];
char *blank = " ", *c = "C++", *Borland = "Borland";
strcpy(destination, Borland);
strcat(destination, blank);
strcat(destination, c);
printf("%s\n", destination);
return 0;
}

5、strchr()

功 能: 在一个字符串中查找给定字符的第一个匹配之处

用 法: char *strchr(char *str, char c);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char string[15];
char *ptr, c = 'r';
strcpy(string, "This is a string");
ptr = strchr(string, c);
if (ptr) {
printf("The character %c is at position: %d\n", c, ptr-string);
} else {
printf("The character was not found\n");
}
return 0;
}

6、strcmp()

功 能: 字符串比较

用 法: int strcmp(char *str1, char *str2); 看 Asic 码,str1>str2,返回值 > 0;两字符串相等,返回 0

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char *buf1 = "aaa", *buf2 = "bbb", *buf3 = "ccc";
int ptr;
ptr = strcmp(buf2, buf1);
if (ptr > 0) {
printf("buffer 2 is greater than buffer 1\n");
} else {
printf("buffer 2 is less than buffer 1\n");
}
ptr = strcmp(buf2, buf3);
if (ptr > 0) {
printf("buffer 2 is greater than buffer 3\n");
} else {
printf("buffer 2 is less than buffer 3\n");
}
return 0;
}

7、strcpy()

功 能: 字符串拷贝

用 法: char *strcpy(char *str1, char *str2);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char string[10];
char *str1 = "abcdefghi";
strcpy(string, str1);
printf("%s\n", string);
return 0;
}

8、strcspn()

功 能: 在字符串中查找第一个给定字符集内容的段

用 法: int strcspn(char *str1, char *str2);

程序例:

#include <stdio.h>
#include <string.h>
#include <alloc.h>
int main(void) {
char *string1 = "1234567890";
char *string2 = "747DC8";
int length;
length = strcspn(string1, string2);
printf("Character where strings intersect is at position %d\n",length);
return 0;
}

9、strdup()

功 能: 将字符串拷贝到新建的位置处

用 法: char *strdup(char *str);

程序例:

#include <stdio.h>
#include <string.h>
#include <alloc.h>
int main(void) {
    char *dup_str, *string = "abcde";
    dup_str = strdup(string);
    printf("%s\n", dup_str);
    free(dup_str);
    return 0;
}

10、stricmp()

功 能: 以大小写不敏感方式比较两个字符串

用 法: int stricmp(char *str1, char *str2);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
    char *buf1 = "BBB", *buf2 = "bbb";
    int ptr;
    ptr = stricmp(buf2, buf1);
    if (ptr > 0) {
        printf("buffer 2 is greater than buffer 1\n");
    }
    if (ptr < 0) {
        printf("buffer 2 is less than buffer 1\n");
    }
    if (ptr == 0) {
        printf("buffer 2 equals buffer 1\n");
    }
    return 0;
}

11、strerror()

功 能: 返回指向错误信息字符串的指针

用 法: char *strerror(int errnum);

程序例:

#include <stdio.h>
#include <errno.h>
int main(void) {
char *buffer;
buffer = strerror(errno);
printf("Error: %s\n", buffer);
return 0;
}

12、strcmpi()

功 能: 将一个字符串与另一个比较, 不管大小写

用 法: int strcmpi(char *str1, char *str2);

程序例:

int main(void) {
char *buf1 = "BBB", *buf2 = "bbb";
int ptr;
ptr = strcmpi(buf2, buf1);
if (ptr > 0) {
printf("buffer 2 is greater than buffer 1\n");
}
if (ptr < 0) {
printf("buffer 2 is less than buffer 1\n");
}
if (ptr == 0) {
printf("buffer 2 equals buffer 1\n");
}
return 0;
}

13、strncmp()

功 能: 字符串比较

用 法: int strncmp(char *str1, char *str2, int maxlen);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char *buf1 = "aaabbb", *buf2 = "bbbccc", *buf3 = "ccc";
int ptr;
ptr = strncmp(buf2,buf1,3);
if (ptr > 0) {
printf("buffer 2 is greater than buffer 1\n");
} else {
printf("buffer 2 is less than buffer 1\n");
}
ptr = strncmp(buf2,buf3,3);
if (ptr > 0) {
printf("buffer 2 is greater than buffer 3\n");
} else {
printf("buffer 2 is less than buffer 3\n");
}
return(0);
}

14、strncmpi()

功 能: 将一个字符串中的一部分与另一个字符串比较, 不管大小写

用 法: int strncmpi(char *str1, char *str2, unsigned maxlen);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char *buf1 = "BBB", *buf2 = "bbb";
int ptr;
ptr = strcmpi(buf2, buf1);
if (ptr > 0) {
printf("buffer 2 is greater than buffer 1\n");
}
if (ptr < 0) {
printf("buffer 2 is less than buffer 1\n");
}
if (ptr == 0) {
printf("buffer 2 equals buffer 1\n");
}
return 0;
}

15、strncpy()

功 能: 字符串拷贝

用 法: char *strncpy(char *destin, char *source, int maxlen);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char string[10];
char *str1 = "abcdefghi";
strncpy(string, str1, 3);
string[3] = '\0';
printf("%s\n", string);
return 0;
}

16、strnicmp()

功 能: 不注重大小写地比较两个字符串

用 法: int strnicmp(char *str1, char *str2, unsigned maxlen);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char *buf1 = "BBBccc", *buf2 = "bbbccc";
int ptr;
ptr = strnicmp(buf2, buf1, 3);
if (ptr > 0) {
printf("buffer 2 is greater than buffer 1\n");
}
if (ptr < 0) {
printf("buffer 2 is less than buffer 1\n");
}
if (ptr == 0) {
printf("buffer 2 equals buffer 1\n");
}
return 0;
}

17、strnset()

功 能: 将一个字符串中的所有字符都设为指定字符

用 法: char *strnset(char *str, char ch, unsigned n);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char *string = "abcdefghijklmnopqrstuvwxyz";
char letter = 'x';
printf("string before strnset: %s\n", string);
strnset(string, letter, 13);
printf("string after strnset: %s\n", string);
return 0;
}

18、strpbrk()

功 能: 在字符串中查找给定字符集中的字符

用 法: char *strpbrk(char *str1, char *str2);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char *string1 = "abcdefghijklmnopqrstuvwxyz";
char *string2 = "onm";
char *ptr;
ptr = strpbrk(string1, string2);
if (ptr) {
printf("strpbrk found first character: %c\n", *ptr);
} else {
printf("strpbrk didn't find character in set\n");
}
return 0;
}

19、strrchr()

功 能: 在字符串中查找指定字符的最后一个出现

用 法: char *strrchr(char *str, char c);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char string[15];
char *ptr, c = 'r';
strcpy(string, "This is a string");
ptr = strrchr(string, c);
if (ptr) {
printf("The character %c is at position: %d\n", c, ptr-string);
} else {
printf("The character was not found\n");
}
return 0;
}

20、strrev()

功 能: 字符串倒转

用 法: char *strrev(char *str);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char *forward = "string";
printf("Before strrev(): %s\n", forward);
strrev(forward);
printf("After strrev(): %s\n", forward);
return 0;
}

21、strset()

功 能: 将一个字符串中的所有字符都设为指定字符

用 法: char *strset(char *str, char c);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char string[10] = "123456789";
char symbol = 'c';
printf("Before strset(): %s\n", string);
strset(string, symbol);
printf("After strset(): %s\n", string);
return 0;
}

22、strspn()

功 能: 在字符串中查找指定字符集的子集的第一次出现

用 法: int strspn(char *str1, char *str2);

程序例:

#include <stdio.h>
#include <string.h>
#include <alloc.h>
int main(void) {
char *string1 = "1234567890";
char *string2 = "123DC8";
int length;
length = strspn(string1, string2);
printf("Character where strings differ is at position %d\n", length);
return 0;
}

23、strstr()

功 能: 在字符串中查找指定字符串的第一次出现

用 法: char *strstr(char *str1, char *str2);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char *str1 = "Borland International", *str2 = "nation", *ptr;
ptr = strstr(str1, str2);
printf("The substring is: %s\n", ptr);
return 0;
}

24、strtod()

功 能: 将字符串转换为 double 型值

用 法: double strtod(char *str, char **endptr);

程序例:

#include <stdio.h>
#include <stdlib.h>
int main(void) {
char input[80], *endptr;
double value;
printf("Enter a floating point number:");
gets(input);
value = strtod(input, &endptr);
printf("The string is %s the number is %lf\n", input, value);
return 0;
}

25、strtok()

功 能: 查找由在第二个字符串中指定的分界符分隔开的单词

用 法: char *strtok(char *str1, char *str2);

程序例:

#include <string.h>
#include <stdio.h>
int main(void) {
char input[16] = "abc,d";
char *p;
/* strtok places a NULL terminator in front of the token, if found */
p = strtok(input, ",");
if (p) {
printf("%s\n", p);
}
/* A second call to strtok using a NULL as the first parameter returns a pointer to the character following the token */
p = strtok(NULL, ",");
if (p) {
printf("%s\n", p);
}
return 0;
}

26、strtol()

功 能: 将字符串转换为长整数

用 法: long strtol(char *str, char **endptr, int base);

程序例:

#include <stdlib.h>
#include <stdio.h>
int main(void) {
char *string = "87654321", *endptr;
long lnumber;
/* strtol converts string to long integer */
lnumber = strtol(string, &endptr, 10);
printf("string = %s long = %ld\n", string, lnumber);
return 0;
}

27、strupr()

功 能: 将字符串中的小写字母转换为大写字母

用 法: char *strupr(char *str);

程序例:

#include <stdio.h>
#include <string.h>
int main(void) {
char *string = "abcdefghijklmnopqrstuvwxyz", *ptr;
/* converts string to upper case characters */
ptr = strupr(string);
printf("%s\n", ptr);
return 0;
}

28、swab()

功 能: 交换字节

用 法: void swab (char *from, char *to, int nbytes);

程序例:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
char source[15] = "rFna koBlrna d";
char target[15];
int main(void) {
swab(source, target, strlen(source));
printf("This is target: %s\n", target);
return 0;
}