strcpy
函數名: strcpy
功 能: 拷貝一個字符串到另一個
用 法: char *strcpy(char *destin, char *source);
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;
}
strncpy
函數名:strncpy
原型：char * strncpy(char *dest, char *src, size_t n);
功能：將字符串src中最多n個字符復制到字符數組dest中(它並不像strcpy一樣遇到NULL才停止復制，而是等湊夠n個字符才開始復制），返回指向dest的指針。
#include <stdio.h>
#include <string.h>
int main(void)
{
char string[10];
char *str1 = "abcdefghi";
strncpy(string, str1,3);
printf("%s\n", string);
return 0;
}
strcat
函數名: strcat
功 能: 字符串拼接函數
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;
}
strchr
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: %d\n", c, ptr-string);
else
printf("The character was not found\n");
return 0;
}
strcmp
函數名: strcmp
功 能: 串比較
用 法: int strcmp(char *str1, char *str2);
看Asic碼，str1>str2，返回值 > 0；兩串相等，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;
}
strnicmp
函數名: strnicmp
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 strnicmp(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 = strnicmp(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;
}
strlen
函數名:strlen
功能: strlen函數求的是字符串的長度，它求得方法是從字符串的首地址開始到遇到第一個'\0'停止計數,如果你只定義沒有給它賦初值，這個結果是不定的，它會從字符串首地址一直記下去，直到遇到'\0'才會停止。
原型: size_t strlen(const char *s);
#include<stdio.h>
#include <string.h>
int main()
{ int i=0;
char *he ="Hello,world";
i=strlen(he);
printf("字符串長度為%d\n",i);
return 0;
} //
運行結果：
字符串長度為11
strcspn
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 %d\n", length);
return 0;
}
strdup
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("%s\n", dup_str);
free(dup_str);
return 0;
}
stricmp
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 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;
}
strerror
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: %s\n", buffer);
return 0;
}
strcmpi
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 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;
}
strnicmp
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 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;
}
strnset
函數名: strnset
功 能: 將一個字符串前n個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: %s\n", string);
strnset(string, letter, 13);
printf("string after strnset: %s\n", string);
return 0;
}
strpbrk
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: %c\n", *ptr);
else
printf("strpbrk didn't find character in set\n");
return 0;
}
strrchr
函數名: strrchr
功 能: 在串中查找指定字符的最后一個出現
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: %d\n", c, ptr-string);
else
printf("The character was not found\n");
return 0;
}
strrev
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(): %s\n", forward);
strrev(forward);
printf("After strrev(): %s\n", forward);
return 0;
}
strset
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(): %s\n", string);
strset(string, symbol);
printf("After strset(): %s\n", string);
return 0;
}
strstr
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: %s\n", ptr);
return 0;
}
strtod
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 %lf\n", input, value);
return 0;
}
strtok
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("%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;
}
strtol
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 = %ld\n", string, lnumber);
return 0;
}
strupr
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;//定義為數組才能修改
/* converts string to upper case characters */
ptr = strupr(string);
printf("%s\n", ptr);
return 0;
}
swab
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: %s\n", target);
return 0;
}
以上都是些C中字符串的常用函數，非常實用，此處記錄，方便以后溫故:)