Sudoku solving matrix, while statement gives an infinite loop - c++

Question

This code should produce a solved sudoku matrix, however the while statement puts it in an infinite loop. Removing the while statement gives me a matrix with some values still 99 or 0. And i can't generate 9 random numbers uniquely one by one.
IF YOU WANT TO RUN AND CHECK THE CODE, REMOVE THE WHILE STATEMENT.
int a[9][9];
int b[9][9];
int inputvalue(int x, int y, int value) //checks horizontally, vertically and 3*3matrix for conflicts
{
int i, j;
for (i = 0; i < 9; i++)
{
if (value == a[x][i] || value == a[i][y])
return 0;
}
for (i = (x / 3) * 3; i <= ((x / 3) * 3) + 2; i++)
{
for (j = (y / 3) * 3; j <= ((y / 3) * 3) + 2; j++)
if (b[i][j] == value)
return 0;
}
return value;
}
int main()
{
int i, j, k;
unsigned int s;
cout << "sudoku\n";
time_t t;
s = (unsigned) time(&t);
srand(s);
for (i = 0; i < 9; i++)
{
for (j = 0; j < 9; j++)
a[i][j] = 99;
}
for (i = 0; i < 9; i++)
{
for (j = 1; j <= 9; j++)//j is basically the value being given to cells in the matrix while k assigns the column no.
while(a[i][k]==99||a[i][k]==0)
{
k = rand() % 9;
a[i][k] = inputvalue(i, k, j);
}
}
for (i = 0; i < 9; i++)
{
for (j = 0; j < 9; j++)
{
cout << a[i][j] << " ";
}
cout << endl;
}
return 0;
getch();
}

Answer 1

You are using assignment =, instead of equality == here:
while(a[i][k]=99||a[i][k]=0)
^ ^
this should be:
while(a[i][k]==99||a[i][k]==0)
a[i][k]=99 will always evaluate to true since 99 is non-zero, although your original code does not compile for me under gcc as it is, so I suspect the code you are running either has some parenthesizes or is slightly different.
Also using k in the while loop before it is initialized is undefined behavior and it is unclear that your termination logic makes sense for a k that is constantly changing for each loop iteration.
Another source of the infinite loop is inputvalue which seems to get stuck returning 0 in some instances, so you need to tweak that a bit to prevent infinite loops.
Also, srand(time(NULL)); is a more common way to initialize the pseudo-random number generator