删除文件 feature

feature/ctype.h/大小写字母转换.c

-#include <ctype.h>
-#include <stdio.h>
-
-int main()
-{
-	printf("输入大写字母：");
-	printf("转为小写字母：%c\n", tolower(getchar()));
-	scanf("%*[^\r\n]%*c");
-	printf("输入小写字母：");
-	printf("转为大写字母：%c\n", toupper(getchar()));
-	return 0;
-}

feature/math.h/圆面积.c

-#include <math.h>
-#include <stdio.h>
-
-double PI = 0;
-
-double pi()
-{
-	if (PI == 0)
-		PI = atan(1) * 4; // 反三角函数arctan
-	return PI;
-}
-
-double area(double radius)
-{
-	return pi()*pow(radius, 2);
-}
-
-int main()
-{
-	double radius;
-	printf("半径：");
-	scanf("%lf", &radius);
-	printf("面积：%.9lf\n", area(radius));
-	return 0;
-}
\ No newline at end of file