C语言string.h中常用字符函数介绍-阿里云开发者社区

开发者社区> 开发与运维> 正文
登录阅读全文

C语言string.h中常用字符函数介绍

简介:

strcpy

函数名: strcpy
 : 拷贝一个字符串到另一个
 : 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

函数名:strncpy
原型:char * strncpy(char *dest, char *src, size_t n);  
功能:将字符串src中最多n个字符复制到字符数组dest(它并不像strcpy一样遇到NULL才停止复制,而是等凑够n个字符才开始复制),返回指向dest的指针。
#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

函数名: strcat
 : 字符串拼接函数
 : 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

函数名: strchr
 : 在一个串中查找给定字符的第一个匹配之处\
 : 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

函数名: strcmp
 : 串比较
 : int strcmp(char *str1, char *str2);
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;
}

strnicmp

函数名: strnicmp
 : 将一个串中的一部分与另一个串比较, 不管大小写
 : 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

函数名:strlen
功能: strlen函数求的是字符串的长度,它求得方法是从字符串的首地址开始到遇到第一个'\0'停止计数,如果你只定义没有给它赋初值,这个结果是不定的,它会从字符串首地址一直记下去,直到遇到'\0'才会停止。
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("字符串长度为%d\n",i);
return 0;
} //
运行结果:
字符串长度为11

strcspn

函数名: strcspn
 : 在串中查找第一个给定字符集内容的段
 : 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

函数名: strdup
 : 将串拷贝到新建的位置处
 : 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

函数名:stricmp
 : 以大小写不敏感方式比较两个串
 : 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

函数名: strerror
 : 返回指向错误信息字符串的指针
 : 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

函数名: strcmpi
 : 将一个串与另一个比较, 不管大小写
 : 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

函数名: strnicmp
 : 不注重大小写地比较两个串
 : 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

函数名: strnset
 : 将一个字符串前n个字符都设为指定字符
 : 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

函数名: strpbrk
 : 在串中查找给定字符集中的字符
 : 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

函数名: strrchr
 : 在串中查找指定字符的最后一个出现
 : 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

函数名: strrev
 : 串倒转
 : 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

函数名: strset
 : 将一个串中的所有字符都设为指定字符
 : 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

函数名: strstr
 : 在串中查找指定字符串的第一次出现
 : 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

函数名: strtod
 : 将字符串转换为double型值
 : 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

函数名: strtok
 : 查找由在第二个串中指定的分界符分隔开的单词
 : 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

函数名: strtol
 : 将串转换为长整数
 : 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

函数名:strupr
 : 将串中的小写字母转换为大写字母
 : char *strupr(char *str);
程序例:
#include <stdio.h>
#include <string.h>
int main(void)
{
char string[ ] = "abcdefghijklmnopqrstuvwxyz", *ptr;//定义为数组才能修改
/* converts string to upper case characters */
ptr = strupr(string);
printf("%s\n", ptr);
return 0;
}

swab

函数名: swab
 : 交换字节
 : 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中字符串的常用函数,非常实用,此处记录,方便以后温故:)


版权声明:本文内容由阿里云实名注册用户自发贡献,版权归原作者所有,阿里云开发者社区不拥有其著作权,亦不承担相应法律责任。具体规则请查看《阿里云开发者社区用户服务协议》和《阿里云开发者社区知识产权保护指引》。如果您发现本社区中有涉嫌抄袭的内容,填写侵权投诉表单进行举报,一经查实,本社区将立刻删除涉嫌侵权内容。

分享:
开发与运维
使用钉钉扫一扫加入圈子
+ 订阅

集结各类场景实战经验,助你开发运维畅行无忧

其他文章
最新文章
相关文章