头文件string.h里的函数

、strcpy

  函数名: 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;

  }

2、strcat

  函数名: strcat

  功 能: 字符串拼接函数

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

  程序例:

  #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;

  }

3、strchr

  函数名: strchr

  功 能: 在一个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;

  }

4、strcmp

  函数名: strcmp

  功 能: 串比较

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

  看Asic码,str1>str2,返回值 > 0;两串相等,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;

  }

5、strncmpi

  函数名: strncmpi

  功 能: 将一个串中的一部分与另一个串比较, 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;

  }

6、strcpy

  函数名: strcpy

  功 能: 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;

  }

7、strcspn

  函数名: strcspn

  功 能: 在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;

  }

8、strdup

  函数名: strdup

  功 能: 将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;

  }

9、stricmp

  函数名: stricmp

  功 能: 以大小写不敏感方式比较两个串

  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;

  }

10、strerror

  函数名: 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;

  }

11、strcmpi

  函数名: strcmpi

  功 能: 将一个串与另一个比较, 不管大小写

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

  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;

  }

  函数名: strncmp

  功 能: 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);

  }

12、strncmpi

  函数名: strncmpi

  功 能: 把串中的一部分与另一串中的一部分比较, 不管大小写

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

  程序例:

  #include <string.h>

  #include <stdio.h>

  int main(void)

  {

  char *buf1 = "BBBccc", *buf2 = "bbbccc";

  int ptr;

  ptr = strncmpi(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;

  }

13、strncpy

  函数名: strncpy

  功 能: 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;

  }

14、strnicmp

  函数名: strnicmp

  功 能: 不注重大小写地比较两个串

  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;

  }

15、strnset

  函数名: strnset

  功 能: 将一个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;

  }

16、strpbrk

  函数名: strpbrk

  功 能: 在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;

  }

17、strrchr

  函数名: strrchr

  功 能: 在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;

  }

18、strrev

  函数名: strrev

  功 能: 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;

  }

19、strset

  函数名: strset

  功 能: 将一个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;

  }

20、strspn

  函数名: strspn

  功 能: 在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;

  }

21、strstr

  函数名: strstr

  功 能: 在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;

  }

22、strtod

  函数名: 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;

  }

23、strtok

  函数名: strtok

  功 能: 查找由在第二个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;

  

  p = strtok(input, ",");

  if (p) printf("%s\n", p);

  

  p = strtok(NULL, ",");

  if (p) printf("%s\n", p);

  return 0;

  }

24、strtol

  函数名: strtol

  功 能: 将串转换为长整数

  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;

  

  lnumber = strtol(string, &endptr, 10);

  printf("string = %s long = %ld\n", string, lnumber);

  return 0;

  }

25、strupr

  函数名: strupr

  功 能: 将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;

  

  ptr = strupr(string);

  printf("%s\n", ptr);

  return 0;

  }

26、swab

  函数名: 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;

  原型:extern char *strstr(char *haystack, char *needle);

  *所在头文件:#include <string.h>

  *功能:从字符串haystack中寻找needle第一次出现的位置(不比较结束符NULL)。

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