Simulating a random walk scenario on a 4x4 board - c++

Question

The problem I am working on is as follows. Imagine a 4x4 chess board on top of which you place a king. The probability of you placing the king on each of the squares is one of the inputs (not necessarily the same for all the squares). The king has to make n number of moves (n is an input). The goal is to run an 'experiment' to find the probability after n moves.
My friend solved the problem by creating a general formula using linear algebra. As a challenge/verification of his answer I want to make this program in c++.
We both start with making one generalization. That is since the board is symmetrical we only consider if the king is at a side, corner or middle square of the board.
C S S C
S M M S
S M M S
C S S C
Therefore, we input only P(S_{initial}), P(C_{initial}), P(M_{initial}), the number of moves the king makes, and the number of 'experiments' we make.
The code for my program is below. My results disagreed with my friend's, so I checked my code by setting n to 1 and P(S_{initial}), P(C_{initial}) and P(M_{initial}) to 1/2, 1/4, and 1/4, respectively. By conditional probability I know that P(S)=59/120, P(C)=21/160, P(M)=181/481. My computations do not agree, so I am sure there is a bug or error in my code, but I cannot track it down. I appreciate any help.
Also I know my code is scruffy and inefficient so I appreciate comments about how to improve it. Thanks for your help.
EDIT: To input the initial probabilities I input 2, 1 and 1 for S, C and M, respectively.
EDIT2: Turned out that I used "=" instead of the operator "==" in my if statements. Thank you #Christopher Oicles. Everything works now as expected.
#include <iostream>
#include <string>
#include <cstdlib>
#include <cmath>
#include <stdio.h>
#include <time.h>
using namespace std;
int S, C, M; //probability 'ratios', i.e. prob of S is S/(S+C+M)
int n; // number of steps
int trials;
int initial(int a,int b,int c); // this 'throws the die' to find where to start and returns 0 for side, 1 for corner, 2 for middle
int step(int a); // this throws the die to make a step and returns the same format
int trial(); //this makes n number of steps, starting at initial(a,b,c) and returns 0,1,2
double data[]={0,0,0}; // the result of the experiment, each element holds the number of times a trial returned the S,C,M where number of s = data[0], I increment this by one every time I run trial();
int main()
{
srand(time(NULL));
for(int i=0;i<3;i++) //reset data array
data[i]=0;
std::cout << "Enter probability ratio of S:";
std::cin >> S;
std::cout << "Enter probability ratio of C:";
std::cin >> C;
std::cout << "Enter probability ratio of M:";
std::cin >> M;
std::cout << "Enter number of steps per trial:";
std::cin >> n;
std::cout << "Enter number of trials:";
std::cin >> trials;
for(int i=0;i<trials;i++)
data[trial()]++;
for(int i=0;i<3;i++)
std::cout << data[i]/trials << " \n";
for(int i=0;i<3;i++)
std::cout<<data[i]<<" ";
cout << "\n \n";
}
int trial(){
int current;// the current place S, C or M or 0,1,2
int next;
current = initial(S,C,M);
for(int i=0;i<n;i++)
{next = step(current);
current = next;}
return current;
}
int initial(int side,int corner,int middle){
int t = rand() % (side+corner+middle); //generates a random number from zero to a+b+c-1
//now we apply the probability
if(t < side)
return 0; //side
if(t >= side && t < (side+corner))
return 1; //corner
if(t>=(side+corner))
return 2; //middle
}
int step(int a){
int t;
switch(a){
case 0: //we are on a side
{t = rand()%5;
if(t < 2){return 0;} //2/5 chance to go to a side
if(t = 2){return 1;} //1/5 chance to go to a corner
if(t > 2){return 2;} //2/5 chance to go to a middle
break;}
case 1: //we are on corner
{t = rand()%3;
if(t < 2){return 0;} //2/3 chance to go to side
if(t = 2){return 2;} //1/3 chance to go to middle
break;}
case 2: //we are on middle
{t = rand()%8;
if(t < 4){return 0;} //1/2 chance go to side
if(t = 4){return 1;} //1/8 chance of corner
if(t > 4){return 2;} //3/8 chance of middle
break;}
}
}