怎么用c++输出一个菱形

Answer 1

最简单
#include <iostream>

using namespace std;

int main()
{
cout << " * " << endl;
cout << " * * " << endl;
cout << " * * " << endl;
cout << " * * " << endl;
cout << " * " << endl;

return 0;
}

另外的实现：
#include <iostream>

using namespace std;

void printlozenge(int n);

int main()
{
int nPoint = 0; // 每个边的点数
do
{
cout << "请输入菱形的大小:";
cin >> nPoint;
printlozenge(nPoint);
}
while (nPoint != -1);

return 0;
}

void printlozenge(int nPoint)
{
int nSpaceLeft = nPoint;
int nSpaceMiddle = 0;
int nSpaceRight = nPoint;
int sign = 1;
for (int i = 1; i < nPoint * 2; ++i)
{
for (int i = 0; i < nSpaceLeft; ++ i) // 输出中间的空格
{
cout << " ";
}

cout << "*"; // 输出的*号

if (nSpaceMiddle != 0) // 如果中间空格不为空
{
for (int i = 1; i < nSpaceMiddle; ++ i) // 输出中间的空格
{
cout << " ";
}
cout << "*"; // 输出的*号
}

cout << endl;

if (i == nPoint) // 绘制了上半部分
{
sign = -1;
}
nSpaceLeft -= sign;
nSpaceMiddle += 2 * sign;
nSpaceRight -= sign;

}
}

Answer 2

我调试过了，你试试看。
#include<iostream>
using namespace std;

void trg1(unsigned int); //正三角（上半个菱形）
void re_trg1(unsigned int); //反三角（下半个菱形）

int main()
{
unsigned int k;
cout<<"请输入半个菱形行数："<<endl;
cin>>k;
trg1(k);
re_trg1(k);
return 0;
}

void trg1(unsigned int n)//正三角（上半个菱形）
{
unsigned i, j;
for(i=1; i<=n; i++)
{
for(j=1; j<(n-i+1); j++)
cout<<' ';
for(j=1; j<=(2*i-1); j++)
cout<<'*';
cout<<endl;

}
}

void re_trg1(unsigned int n)//反三角（下半个菱形）
{
unsigned i, j;
for(i=1; i<=n; i++)
{
for(j=1; j<=(i-1); j++)
cout<<' ';

for(j=1; j<=(2*(n-i)+1); j++)
cout<<'*';
cout<<endl;

}
}

Answer 3

#include <iostream>

using namespace std;

void printlozenge(int n);

int main()
{
int nPoint = 0; do
{
cout << "";
cin >> nPoint;
printlozenge(nPoint);
}
while (nPoint != -1);

return 0;
}

void printlozenge(int nPoint)
{
int nSpaceLeft = nPoint;
int nSpaceMiddle = 0;
int nSpaceRight = nPoint;
int sign = 1;
for (int i = 1; i < nPoint * 2; ++i)
{
for (int i = 0; i < nSpaceLeft; ++ i) // {
cout << " ";
}

cout << "*"; if (nSpaceMiddle != 0) {
for (int i = 1; i < nSpaceMiddle; ++ i) cout << " ";
}
cout << "*"; }

cout << endl;

if (i == nPoint) {
sign = -1;
}
nSpaceLeft -= sign;
nSpaceMiddle += 2 * sign;
nSpaceRight -= sign;

}
}