【C语言】实现大小写转换的三种方法

实现大小写转换的三种方法

方法一：

#include
#include
int main()
{
 char str[] = "AbCdEf";
 char c;
 int i = 0;
 while (str[i] != '\0')
 {
  c = str[i];
  if (c >= 'A' && c <= 'Z')
  {
   c = c + 32;
  }
  else if (c >= 'a' && c <= 'z')
  {
   c = c - 32;
  }
      printf("%c",c);
  i++;
 }
 printf("\n");
 system("pause");
 return 0;
}

运行结果如下：

方法二：

#include
#include
int main()
{
 char str[] = "AbCdEf";
 char c;
 int i = 0;
 while (str[i] != '\0')
 {
  c = str[i];
  if (c >= 'A' && c<='Z' || c>='a' && c <= 'z')
  {
   c ^= 32;
  }
  printf("%c", c);
  i++;
 }
 printf("\n");
 system("pause");
 return 0;
}

运行结果如下：

方法三：

#include
#include
#include
int main()
{
 char str[] = "AbCdEf";
 char c;
 int i = 0;
 while (str[i] != '\0')
 {
  c = str[i];
  if (isupper(c))
  {
   c = tolower(c);
  }
  else if (islower(c))
  {
   c = toupper(c);
  }
  printf("%c", c);
  i++;
 }
 printf("\n");
 system("pause");
 return 0;
}

运行结果如下：