(1)编写程序数一下0-100之间9的个数:
#include<stdio.h>
#include<stdlib.h>
int main()
{
int cnt = 0;
for (int i = 0; i <= 100; ++i)
{
if (i % 10 == 9)//取个位
{
++cnt;
}
if (i / 10 % 10 == 9)//取十位
{
++cnt;
}
}
printf("%d\n", cnt);
system("pause");
return 0;
}
( 2)计算1/1-1/2+1/3-1/4+…+1/99-1/100
#include<stdio.h>
#include<stdlib.h>
int main()
{
double sum = 0;
for (int i = 1; i <= 100; i=i+2)//求i等于奇数时的和,
{
sum = sum + 1.0 / i;
}
for (int i = 2; i <= 100; i = i + 2)//求i等于偶数时的和,
{
sum = sum - 1.0 / i;
}
printf("%lf\n", sum);
system("pause");
return 0;
}
(3)将两个数组中的数字交换:(数组中元素个数相等)
#include<stdio.h>
#include<stdlib.h>
int main()
{
int a[] = { 1, 2, 3, 4 };
int b[] = { 5, 6, 7, 8 };
int tmp = 0;
for (int i = 0; i < sizeof(a) / sizeof(a[0]); ++i)//遍历一下数组,创建临时变量交换a[i],b[i]的值,
{
tmp = a[i];
a[i] = b[i];
b[i] = tmp;
}
for (int i = 0; i < sizeof(a) / sizeof(a[0]); ++i)//循环打印数组a的值
{
printf("%d ", a[i]);
}
printf("\n");
for (int i = 0; i < sizeof(b) / sizeof(b[0]); ++i)//循环打印数组b的值,
{
printf("%d ", b[i]);
}
printf("\n");
system("pause");
return 0;
}
(4)打印菱形
#include<stdio.h>
#include<stdlib.h>
void PrintfLine(char g_blank, char g_start)
{
for (int i = 1; i <= g_blank; ++i)
{
printf(" ");
}
for (int i = 1; i <= g_start; ++i)
{
printf("*");
}
printf("\n");
}
void PrintfLingxing(int n)
{
for (int i = 1; i < n; ++i)
{
PrintfLine(n - i, 2 * i - 1);
}
PrintfLine(0, 2 * n - 1);
for (int i = n - 1; i > 0; --i)
{
PrintfLine(n - i, 2 * i - 1);
}
}
int main()
{
PrintfLingxing(10);
system("pause");
return 0;
}