c字符串函數

函數名: strchr
功 能: 在一個串中查找給定字符的第一個匹配之處
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: %dn, c, ptr-string);
else
printf(The character was not foundn);
return 0;
}


函數名: strncmpi
功 能: 將一個串中的一部分與另一個串比較, 不管大小寫
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 1n);
if (ptr < 0)
printf(buffer 2 is less than buffer 1n);
if (ptr == 0)
printf(buffer 2 equals buffer 1n);
return 0;
}




函數名: strcspn
功 能: 在串中查找第一個給定字符集內容的段
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 %dn, length);
return 0;
}



函數名: strdup
功 能: 將串拷貝到新建的位置處
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(%sn, dup_str);
free(dup_str);
return 0;
}



函數名: stricmp
功 能: 以大小寫不敏感方式比較兩個串
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 1n);
if (ptr < 0)
printf(buffer 2 is less than buffer 1n);
if (ptr == 0)
printf(buffer 2 equals buffer 1n);
return 0;
}


函數名: strerror
功 能: 返回指向錯誤信息字符串的指針
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: %sn, buffer);
return 0;
}



函數名: strcmpi
功 能: 將一個串與另一個比較, 不管大小寫
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 1n);
if (ptr < 0)
printf(buffer 2 is less than buffer 1n);
if (ptr == 0)
printf(buffer 2 equals buffer 1n);
return 0;
}



函數名: strncmp
功 能: 串比較
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 1n);
else
printf(buffer 2 is less than buffer 1n);
ptr = strncmp(buf2,buf3,3);
if (ptr > 0)
printf(buffer 2 is greater than buffer 3n);
else
printf(buffer 2 is less than buffer 3n);
return(0);
}


函數名: strncmpi
功 能: 把串中的一部分與另一串中的一部分比較, 不管大小寫
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 1n);
if (ptr < 0)
printf(buffer 2 is less than buffer 1n);
if (ptr == 0)
printf(buffer 2 equals buffer 1n);
return 0;
}


函數名: strncpy
功 能: 串拷貝
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] = '';
printf(%sn, string);
return 0;
}


函數名: strnicmp
功 能: 不注重大小寫地比較兩個串
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 1n);
if (ptr < 0)
printf(buffer 2 is less than buffer 1n);
if (ptr == 0)
printf(buffer 2 equals buffer 1n);
return 0;
}



函數名: strnset
功 能: 將一個串中的所有字符都設為指定字符
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: %sn, string);
strnset(string, letter, 13);
printf(string after strnset: %sn, string);
return 0;
}


函數名: strpbrk
功 能: 在串中查找給定字符集中的字符
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: %cn, *ptr);
else
printf(strpbrk didn't find character in setn);
return 0;
}



函數名: strrchr
功 能: 在串中查找指定字符的最後一個出現
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: %dn, c, ptr-string);
else
printf(The character was not foundn);
return 0;
}



函數名: strrev
功 能: 串倒轉
用 法: char *strrev(char *str);
程序例:
#include <string.h>
#include <stdio.h>
int main(void)
{
char *forward = string;
printf(Before strrev(): %sn, forward);
strrev(forward);
printf(After strrev(): %sn, forward);
return 0;
}

函數名: strset
功 能: 將一個串中的所有字符都設為指定字符
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(): %sn, string);
strset(string, symbol);
printf(After strset(): %sn, string);
return 0;
}



函數名: strspn
功 能: 在串中查找指定字符集的子集的第一次出現
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 %dn, length);
return 0;
}


函數名: strstr
功 能: 在串中查找指定字符串的第一次出現
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: %sn, ptr);
return 0;
}


函數名: strtod
功 能: 將字符串轉換為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 %lfn, input, value);
return 0;
}



函數名: strtok
功 能: 查找由在第二個串中指定的分界符分隔開的單詞
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(%sn, 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(%sn, p);
return 0;
}



函數名: strtol
功 能: 將串轉換為長整數
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 = %ldn, string, lnumber);
return 0;
}

函數名: strupr
功 能: 將串中的小寫字母轉換為大寫字母
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(%sn, ptr);
return 0;
}



函數名: swab
功 能: 交換字節
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: %sn, target);
return 0;
}