c 大小寫轉換

#include<stdio.h>


//void upper(char s[]) //數組名做參數退化爲指針
void upper(char *s1, char *s2)
{
 int i;
 while(*(s1+i) != '\0')
 //for(i = 0; i < sizeof(s)/sizeof(char); i++) //這裏sizeof(s)就是指針的大小4 byte了
 {
  if(s1[i] >= 'a' && s1[i] <= 'z')
   s2[i] = s1[i] -('a' - 'A');
  else
   s2[i] = s1[i];
  i++;
 }
 s2[i] = '\0';
}

//void upper(char s[]) //數組名做參數退化爲指針
void upper2(char *s1)
{
 int i;
 while(*(s1+i) != '\0')
 //for(i = 0; i < sizeof(s)/sizeof(char); i++) //這裏sizeof(s)就是指針的大小4 byte了
 {
  if(s1[i] >= 'a' && s1[i] <= 'z')
   s1[i] = s1[i] -('a' - 'A');
  i++;
 }
}

int main()
{
 char a[] = "AbCdEfGg";
 char b[100];
 printf("%s\n", a);  //AbCdEfGg
 printf("%c\n", *a);  //A
 printf("%c\n", a[0]); //A
 //upper(a, b);
 upper2(a);
 printf("%s\n", a);  //ABCDEFGG
}