1:菱形输出星号;2:打印100~999所有的水仙花数;3:求Sn=a+aa+aaa+aaaa+aaaaa的前五项之和;4:从标准输入读取C源代码，验证所有的花括号都是正确的成对出现

//菱形输出星号
#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
int i = 0, j = 0, star = 0,line = 0, n;
printf("please input a int number:");
scanf("%d", &n);
printf("\n");
for (i = 1; i <= 2 * n - 1; i++)
{
line = i;
if (i > n) line = 2 * n - line;//1 2 3 4 3 2 1
for (j = n; j > line; j--)
{
printf(" ");
}
for (star = 2 * line - 1; star > 0; star--)
{
printf("*");
}
printf("\n");
}
system("pause");
return 0;
}

//打印100~999所有的水仙花数
#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
int a = 0, b = 0, c = 0;
printf("100~999的水仙花数有:\n");
for (int i = 100; i < 1000; i++)
{
a = i / 100;
b = i / 10-a*10;
c = i - 100 * a - 10 * b;
if (a*a*a + b*b*b + c*c*c == i)
{
printf("%d ", i);
}
}
printf("\n");
system("pause");
return 0;
}

//求Sn=a+aa+aaa+aaaa+aaaaa的前五项之和
#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
int sum = 0, n = 0,t = 0;
printf("please input a int number of 0~9:");
scanf("%d", &n);
t = n;
printf("sum=");
for (int i = 0; i < 5; i++)
{
if (i == 4) printf("%d", n);
else printf("%d+", n);
sum = sum + n;
n = n * 10 + t;
}
printf("=%d\n", sum);
system("pause");
return 0;
}

//从标准输入读取C源代码，并验证所有的花括号都是正确的成对出现
#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#define EOF -1
int main()
{
int ch , i = 0;
ch = getchar();
while (ch != EOF)
{
if (ch == '}')
{
i--;
if (i < 0)
{
printf("unmatched!");
system("pause");
return 0;
}
}
if (ch == '{')
i++;
ch = getchar();
}
{
if (i == 0)
printf("matched!");
else
printf("unmatched!");
}
system("pause");
return 0;
}