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.html

void 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c
void 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();

}