C语言常用字符串函数

2019-11-06 09:35:16

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C语言字符串函数速查

#define _CRT_SECURE_NO_WARNINGS#include <stdio.h>#include <stdlib.h>#include <string.h>//字符串相关函数//strcat字符串拼接函数//在线API文档：//http://www.kuqin.com/clib/string/strcpy.htmlvoid main(void){ char dest[50]; char *a = "china"; char *b = " is powerful!"; strcpy(dest,a); strcat(dest,b); PRintf("%s/n",dest); system("pause");}//strchr在一个串中查找给定字符的第一个匹配之处void main(void){ char *str = "I want go to USA!"; //U元素的指针 //str+3 char* p = strchr(str,'w'); if (p){ printf("索引位置：%d/n", p - str); } else{ printf("没有找到"); } system("pause");}//strstr 从字符串haystack中寻找needle第一次出现的位置void main(void){ char *haystack = "I want go to USA!"; char *needle = "to"; //U元素的指针 char* p = strstr(haystack, needle); if (p){ printf("索引位置：%d/n", p - haystack); } else{ printf("没有找到"); } system("pause");}//strcmp 比较字符串 strcmpi 比较字符串，忽略大小写void main(void){ char *str1 = "abc"; char *str2 = "ABC"; //int r = strcmpi(str1, str2); int r = _strcmpi(str1, str2); printf("%d/n",r); //str1 > str2 if (r > 0){ printf("str1 大于str2/n"); } else if (r == 0){ printf("str1 等于str2/n"); } //str1 < str2 else if (r < 0){ printf("str1 小于str2/n"); } system("pause");}//strset 把字符串s中的所有字符都设置成字符cvoid main(void){ char str[] = "internet change the world!"; _strset(str,'w'); printf("%s/n",str); system("pause");}//strrev 把字符串s的所有字符的顺序颠倒过来void main(void){ char str[] = "internet change the world!"; _strrev(str); printf("%s/n", str); system("pause");}//atoi 字符串转为int类型//atol()：将字符串转换为长整型值void main(void){ char* str = "a78"; int r = atoi(str); printf("%d/n", r); system("pause");}// 字符串转为double类型void main(void){ char* str = "77b8b"; char** p = NULL; //char* p = str + 2; //参数说明：str为要转换的字符串，endstr 为第一个不能转换的字符的指针 double r = strtod(str,p); printf("%lf/n", r); printf("%#x/n", p); system("pause");}//strupr转换为大写void main(void){ char str[] = "CHINA motherland!"; _strupr(str); printf("%s/n",str); system("pause");}//转换为小写void mystrlwr(char str[],int len){ int i = 0; for (; i < len; i++){ //A-Z 字母 a-Z if (str[i] >= 'A' && str[i] <= 'Z'){ str[i] = str[i]-'A' + 'a'; } } }void main(void){ char str[] = "CHINA motherland!"; mystrlwr(str,strlen(str)); printf("%s/n", str); system("pause");}//练习：删除字符串中指定的字符void delchar(char *str, char del){ char *p = str; while (*str != '/0') { if (*str != del) { *p++ = *str; } str++; } *p = '/0';}//删除最后一个字符int main(){ char str[] = "vencent ppQQ"; delchar(str,'t'); printf("%s/n", str); system("pause");}//java String replaceAll //StringBuffer buff.deleteCharAt(buff.length()-1);//删除最后一个字符void main(void){ char str[] = "internet,"; str[strlen(str) - 1] = '/0'; printf("%s/n", str); //作业：realloc实现StringBuffer的拼接，而不是一开始开辟一个很大的数组 //结构体StringBuffer system("pause");}//memcpy 由src所指内存区域复制count个字节到dest所指内存区域void main(void){ char src[] = "C,C++,Java"; char dest[20] = {0}; //字节 memcpy(dest,src,5); printf("%s/n",dest); system("pause");}//memchr 从buf所指内存区域的前count个字节查找字符ch。void main(void){ char src[] = "C,C++,Java"; char ch = 'C'; //字节 (分段截取) char* p = memchr(src+3, ch, 5); if (p){ printf("索引：%d/n", p - src); } else{ printf("找不到/n"); } system("pause");}//memmove 由src所指内存区域复制count个字节到dest所指内存区域。void main(){ char s[] = "Michael Jackson!"; //截取的效果 memmove(s, s + 8, strlen(s) - 8 - 1); s[strlen(s) - 8] = 0; printf("%s/n", s); getchar();}//在字符串s1中寻找字符串s2中任何一个字符相匹配的第一个字符的位置，空字符NULL不包括在内void main(){ char *s1 = "Welcome To Beijing"; char *s2 = "to"; char *p; p = strpbrk(s1, s2); if (p) printf("%s/n", p); else printf("Not Found!/n"); p = strpbrk(s1, "Da"); if (p) printf("%s", p); else printf("Not Found!"); getchar();}

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