Pfthb

I have a vector of vectors filled with characters from a text file. It is essentially a simple outbreak simulator, with 'i' characters being infected, and 's' characters being susceptible to infection. The point is to run through the matrix and if it comes across an 'i', it then changes all 's' around it into an 'i'. I run into a problem when checking the elements around it due to checking positions out of the bounds on the edges of the matrix. Is there a way to check these bounds in my if statements?

Here is the code:

for (int i = 0; i < population.size(); i++) 
 for(int j = 0; j < population[i].size(); j++) 

 if(population[i][j] == 'i') 

 if(population[i-1][j] == 's') 
 population[i-1][j] = 'i';
 
 if(population[i-1][j+1] == 's') 
 population[i-1][j+1] = 'i';
 
 if(population[i][j+1] == 's') 
 population[i][j+1] = 'i';
 
 if(population[i+1][j+1] == 's') 
 population[i+1][j+1] = 'i'; 
 
 if(population[i+1][j] == 's') 
 population[i+1][j] = 'i';
 
 if(population[i+1][j-1] == 's') 
 population[i+1][j-1] = 'i';
 
 if(population[i][j-1] == 's') 
 population[i][j-1] = 'i';
 
 
 
 

Instead of directly referencing a particular array entry, you could do something like the following:

void checkForInfectionAndInfectIfNeeded(int i, int j) 
 for (int row = -1; row <= 1; row++) 
 for (int column = -1; column <=1; column++) 
 infect(i + row, j + column);
 
 


void infect(int i, int j) j >= population[j].size()) 
 return;
 else 
 population[i][j] = 'i';
 

This way, the infect method is the only that checks the boundaries, and you replace your long list of manually checking the surrounding locations with two loops.