为什么这串代码无法输出结果？

Question

#include<iostream>
#include<iomanip>
using namespace std;
int main()
{const int M=10;
int x[M][M],m,a,b,c;
cout<<"请输入m值";
cin>>m;
x[0][0]=m;
for(a=1,b=m-1;b>0;a++,b--)
{x[a][a]=x[a-1][a-1]+b;}
while(b<9)
    {b=1;
        for(a=0,b;a<m;a++,b++)
{x[a][b]=x[a][a]-b;}
        b++;}
for(a=0;a<m;a++)
{for(b=0;b<m;b++)
{if(x[a][b]>0)
{cout<<x[a][b]<<"    ";}
cout<<endl;}}
}
![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/559504296256168.png "#left")

Answer 1

while循环内每次都将b赋值为1，导致其到不了9，死循环。移到while之前就行