#include <
stdio.h>
#include <
string.h>
#include <
stdlib.h>
#include <ctype.h>
// 把
字符串转换为小写
char* str2lower(char *str)
{
char *p = str;
while (*str){
*str = tolower(*str);
str++;
}
return p;
}
// 把字符串转换为大写
char* str2upper(char *str)
{
char *p = str;
while (*str){
*str = toupper(*str);
str++;
}
return p;
}
/* 使用方法:
* command [A|a] string
* 参数说明:
* string是要转换的字符串
* [A|a]表示将字符串string转化为大写还是小写
*/
int main(int argc, char *argv[])
{
if (argc != 3 || strlen(argv[1]) != 1){
printf("usage: command [A|a] string\n");
return EXIT_FAILURE;
}
if (isupper(argv[1][0]))
printf("字符串的大写是:%s\n", str2upper(argv[2]));
else if (islower(argv[1][0]))
printf("字符串的小写是:%s\n", str2lower(argv[2]));
else
printf("原始的字符串是:%s\n", argv[2]);
return EXIT_SUCCESS;
}