C語言字符串函數大全

程序開頭要聲明#include <string.h>函數名: stpcpy功  能: 拷貝一個字符串到另一個用  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;}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;}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; }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; }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 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;}函數名: strcpy功  能: 串拷貝用  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; }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; }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; }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;}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;}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;}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 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);}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 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] = '\0';   printf("%s\n", 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 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;}函數名: strnset功  能: 將一個串中的所有字符都設爲指定字符用  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;}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;}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: %d\n", c, ptr-string);   else      printf("The character was not found\n");   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(): %s\n", forward);   strrev(forward);   printf("After strrev():  %s\n", forward);   return 0;}函數名: strset功  能: 將一個串中的所有字符都設爲指定字符用  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;}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 %d\n", 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: %s\n", ptr);   return 0;}函數名: strtod功  能: 將字符串轉換爲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;}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;}函數名: strtol功  能: 將串轉換爲長整數用  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;}函數名: strupr功  能: 將串中的小寫字母轉換爲大寫字母用  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("%s\n", 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: %s\n", target);   return 0;}

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