C++ program refuses to set value to matrix [closed] - c++

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Ok, so I have this code(declarations are global). It is basically a simple chess program and this part of the program tries to assess which fields are threatened by black pieces at a certain point in time. If a field is threatened, the c3[][] value of it goes from 0 to 1. The problem is that even after I made 100% sure the if conditions are met, the program would still refuse to set the c3[][] values to 1. And even worse, the if(c2[I][J]==9||c2[I][J]==10) partworks fine, which makes it even harder for me to identify the problem. I can provide the whole source code if necessary.
void atacalb()
{
int I,J;
for(I=1;I<=8;I++)
for(J=1;J<=8;J++)
{if(c2[I][J]==7){c3[I+1][J+1]=1,c3[I+1][J-1]=1;}
if(c2[I][J]==8){c3[I+2][J+1]=1,c3[I+2][J-1]=1,c3[I+1][J+2]=1,c3[I-1][J+2]=1,c3[I-2][J+1]=1,c3[I-2][J-1]=1,c3[I+1][J-2]=1,c3[I-1][J-2]=1;}
int z,x,ok;
for(I=1;I<=8;I++)
for(J=1;J<=8;J++)
if(c2[I][J]==9||c2[I][J]==10)
{
z=I,x=J,ok=1;
while((z<=8||x<=8)&&ok)
{z++,x++;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
z=I,x=J,ok=1;
while((z<=8||x>=1)&&ok)
{i++,j--;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
z=I,x=J,ok=1;
while((z>=1||x>=1)&&ok)
{z--,x--;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
z=I,x=J,ok=1;
while((z>=1||x<=8)&&ok)
{z--,x++;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
}
if(c2[I][J]==12||c2[I][J]==10)
{z=I,x=J,ok=1;
while(x<=8&&ok==1)
{x++;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
z=I,x=J,ok=1;
while(z<=8&&ok==1)
{z++;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
z=I,x=J,ok=1;
while(z>=1&&ok==1)
{z--;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
z=I,x=J,ok=1;
while(x>=1&&ok==1)
{x--;
if(c2[z][x]==0)c3[z][x]=1;
else {c3[z][x]=1,ok=0;}
}
}
}
}
int main()
{//some code
atacalb();
//some more code
}

Answer 1

Using proper indention and bracket placement is key here! I stripped done all the code wich actually processes stuff and just left loops and if-statements in for readability. I then properly indented the code how the compiler gets to see it
int I, J;
for(I = 1; I <= 8; I++)
for(J = 1; J <= 8; J++) {
if(c2[I][J] == 7) {
}
if(c2[I][J] == 8) {
}
for(I = 1; I <= 8; I++)
for(J = 1; J <= 8; J++) /*!*/
if(c2[I][J] == 9 || c2[I][J] == 10) { ///< only this gets processed by the loop
while((z <= 8 || x <= 8) && ok){
if(c2[z][x] == 0) {
}
else {
}
}
while((z <= 8 || x >= 1) && ok) {
if(c2[z][x] == 0) {
}
else {
}
}
while((z >= 1 || x >= 1) && ok) {
if(c2[z][x] == 0) {
}
else {
}
}
while((z >= 1 || x <= 8) && ok) {
if(c2[z][x] == 0) {
}
else {
}
}
}
if(c2[I][J] == 12 || c2[I][J] == 10) { ///< not this
while(x <= 8 && ok == 1) {
if(c2[z][x] == 0) {
}
else {
}
}
while(z <= 8 && ok == 1) {
if(c2[z][x] == 0) {
}
else {
}
}
while(z >= 1 && ok == 1) {
if(c2[z][x] == 0) {
}
else {
}
}
while(x >= 1 && ok == 1) {
if(c2[z][x] == 0) {
}
else {
}
}
}
}
The problem is marked in the code above: the for loops (marked /*!*/) will not process the if-statement (if(c2[I][J] == 12 || c2[I][J] == 10)) only the first if statement after the marked loop. A way to fix this would be to either use a if-else-statement in this case or surround all your loops with curly braces as it should be done anyway. This is so that you can add and remove lines inside the brackets and can be sure that they will be processed as well. Also it makes the program flow more clear to the non-compiler-reader (i.e. the human being which tries to understand the code).
Also depending on the size of c2 which is probably an 8x8 array you should change the loop conditions. C++ uses 0-indexed arrays so an array with a size of 8 will be accessed by the indices from 0 - 7 not 1 - 8. So for example
for(I = 1; I <= 8; I++)
for(J = 1; J <= 8; J++) {
//...
should most likely be
for(I = 0; I < 8; I++) // smaller not smaller-equal
for(J = 0; J < 8; J++) {
// ...

Answer 2

You need to stop trying to play c++ golf if you want to debug basic problems in your code. Add white space where appropriate, including new lines.
Set a breakpoint on the line in question that sets your array location to 1, then step through the code with a watch on that variable, line by line. I can guarantee its not "refusing to set it." Its a branch in your code that you are not expecting to execute executing.