string重点函数集合
<<string重点函数集合>>
1函数名:strcpy
功能:拷贝一个字符串到另一个
用法:char *strcpy(char *destin, char *source);
程序例:
#include<stdio.h>
#include <string.h>
intmain(void)
{
char string[10];
char *str1 = "abcdefghi";
strcpy(string,str1);
printf("%s\n", string);
return 0;
}
2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>
intmain(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>
intmain(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>
intmain(void)
{
char *buf1 = "aaa", *buf2 = "bbb",*buf3 = "ccc";
int ptr;
ptr= strcmp(buf2, buf1);
if (ptr > 0)
printf("buffer2 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 isless than buffer 3\n");
return0;
}
5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>
intmain(void)
{
char *buf1 = "BBB", *buf2= "bbb";
int ptr;
ptr= strcmpi(buf2, buf1);
if(ptr > 0)
printf("buffer 2is greater than buffer 1\n");
if(ptr < 0)
printf("buffer 2is less than buffer 1\n");
if(ptr == 0)
printf("buffer 2equals buffer 1\n");
return0;
}
功能：顺序在字符串s1中搜寻与s2中字符的第一个相同字符，返回这个字符在S1中第一次出现的位置。
说明：（返回第一个出现的字符在s1中的下标值，亦即在s1中出现而s2中没有出现 的子串的长度。）
简单地说，若strcspn()返回的数值为n，则代表字符串s1开头连续有n个字符都不含字符串s2内的字符
用法:int
strcspn(char *str1, char *str2);
程序例:
#include<stdio.h>
#include <string.h>
intmain(void)
{
char *string1 = "1234567890";
char *string2 = "747DC8";
int length;
length= strcspn(string1, string2);
printf("Character wherestrings intersect is at position %d\n", length);
return0;
}
7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>
intmain(void)
{
char *dup_str, *string = "abcde";
dup_str= strdup(string);
printf("%s\n", dup_str);
free(dup_str);//这是C语言C++用的是delete(dup_str);
return0;
}
8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>
intmain(void)
{
char *buf1 = "BBB", *buf2 = "bbb";
int ptr;
ptr= stricmp(buf2, buf1);
if(ptr > 0)
printf("buffer 2 is greater than buffer1\n");
if(ptr < 0)
printf("buffer 2 is less than buffer1\n");
if(ptr == 0)
printf("buffer 2 equals buffer 1\n");
return0;
}
9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>
intmain(void)
{
char *buffer;
buffer = strerror(errno);
printf("Error: %s\n",buffer);
return 0;
}
10函数名:strncmp
功能：比较字符串的前maxlen个字符
形式：intstrncmp(char
*str1, char *str2, int maxlen)
程序例:
#include<string.h>
#include <stdio.h>
intmain(void)
{
char *buf1 = "aaabbb", *buf2 = "bbbccc",*buf3 = "ccc";
int ptr;
ptr= strncmp(buf2,buf1,3);
if (ptr > 0)
printf("buffer 2 is greaterthan 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 greaterthan buffer 3\n");
else
printf("buffer 2 is less than buffer 3\n");
return(0);
}
11函数名:strncpy
功能:串拷贝，将第二个字符串前maxlen个字符拷贝给第一个字符串
用法:char
*strncpy(char *destin, char *source, int maxlen);
程序例:
#include<stdio.h>
#include <string.h>
intmain(void)
{
char string[10];
char *str1 = "abcdefghi";
strncpy(string,str1, 3); //只复制三个字符
string[3] = '\0';
printf("%s\n", string);
return 0;
}
12函数名:strpbrk
功能：依次检验字符串s1中的字符，当被检验字符在字符串s2中也包含时，则停止检验，并返回该字符位置，空字符NULL不包括在内。
说明：返回s1中第一个满足条件的字符的指针，如果没有匹配字符则返回空指针NULL。
用法:char
*strpbrk(char *str1, char *str2);
程序例:
#include<stdio.h>
#include <string.h>
intmain(void)
{
char *string1 ="abcdefghijklmnopqrstuvwxyz";
char*string2 = "onm";
char *ptr;
ptr= strpbrk(string1, string2);
if(ptr)
printf("strpbrk foundfirst character: %c\n", *ptr);
else
printf("strpbrk didn't find character in set\n");
return0;
}
13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>
intmain(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;
}
14函数名:strrev
功能:串倒转（VC支持）
用法:char *strrev(char *str);
程序例:
#include<string.h>
#include <stdio.h>
intmain(void)
{
char *forward = "string";
printf("Beforestrrev(): %s\n", forward);
strrev(forward);
printf("After strrev(): %s\n", forward);
return 0;
}
15函数名:strset
功能:将一个串中的所有字符都设为指定字符（VC支持）
用法:char *strset(char *str, char c);
程序例:
#include<stdio.h>
#include <string.h>
intmain(void)
{
char string[10] = "123456789";
char symbol = 'c';
printf("Beforestrset(): %s\n", string);
strset(string,symbol);
printf("After strset(): %s\n",string);
return 0;
}
16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>
intmain(void)
{
char input[80], *endptr;
double value;
printf("Entera floating point number:");
gets(input);
value = strtod(input, &endptr);
printf("Thestring is %s the number is %lf\n", input, value);
return 0;
}
17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>
intmain(void)
{
char input[16] = "abc,d";
char *p;
/*strtok places a NULL terminator
in front of thetoken, if found */
p = strtok(input, ",");
if (p) printf("%s\n", p);
/*A second call to strtok using a NULL
as the firstparameter returns a pointer
to the characterfollowing the token */
p = strtok(NULL, ",");
if (p) printf("%s\n", p);
return 0;
}
18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>
intmain(void)
{
char *string ="abcdefghijklmnopqrstuvwxyz", *ptr;
/*converts string to upper case characters */
ptr =strupr(string);
printf("%s\n", ptr);
return 0;
}
19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>
charsource[15] = "rFna koBlrna d";
char target[15];
intmain(void)
{
swab(source, target,strlen(source));
printf("This is target: %s\n",target);
return 0;
原型：externchar *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)。
说明：返回指向第一次出现needle位置的指针，如果没找到则返回NULL。
