Generate .pgm and .yaml from a "grid.txt"

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With the code below I load a map to memory and generate a "grid_inflate.txt" that contains a matrix of 0's and 1's, where i inflate the obstacles (change some 0's to 1 basically). Know I need to generate another .pgm and .yaml from this "grid_inflate.txt" and I don't know how.

#include <ros/ros.h>
#include <nav_msgs/GetMap.h>
#include <vector>
#include <fstream>

using namespace std;

// grid map
int rows;
int cols;
double mapResolution;
vector<vector<bool> > grid;

bool requestMap(ros::NodeHandle &nh);
void readMap(const nav_msgs::OccupancyGrid& msg);
void printGridToFile();

int main(int argc, char** argv)
{
    ros::init(argc, argv, "mapping");
    ros::NodeHandle nh;

    if (!requestMap(nh))
        exit(-1);

    printGridToFile();

    return 0;
}

bool requestMap(ros::NodeHandle &nh)
{
    nav_msgs::GetMap::Request req;
    nav_msgs::GetMap::Response res;

    while (!ros::service::waitForService("static_map", ros::Duration(3.0))) {
         ROS_INFO("Waiting for service static_map to become available");
    }

    ROS_INFO("Requesting the map...");
    ros::ServiceClient mapClient = nh.serviceClient<nav_msgs::GetMap>("static_map");

    if (mapClient.call(req, res)) {
        readMap(res.map);
        return true;
    }
    else {
        ROS_ERROR("Failed to call map service");
        return false;
    }
}

void readMap(const nav_msgs::OccupancyGrid& map)
{
    ROS_INFO("Received a %d X %d map @ %.3f m/px\n",
            map.info.width,
            map.info.height,
            map.info.resolution); 
    rows = map.info.height;
    cols = map.info.width;
    mapResolution = map.info.resolution;

    // Dynamically resize the grid
    grid.resize(rows);
    for (int i = 0; i < rows; i++) {
        grid[i].resize(cols);
    } 
    int currCell = 0;
    for (int i = 0; i < rows; i++)  {
        for (int j = 0; j < cols; j++)      {
            if (map.data[currCell] == 0) // unoccupied cell
                grid[i][j] = false;
            else
                grid[i][j] = true; // occupied (100) or unknown cell (-1)
            currCell++;
        }
    }

    for (int i = 5 ; i < grid.size(); i++) {        
        for (int j = 5; j < grid[0].size(); j++) {
            if(grid[i][j] == true){
                if(grid[i][j-1] == false){
                    grid[i][j-1] = true;
                }
                if(grid[i-1][j] == false){
                    grid[i-1][j] = true;
                }
                if(grid[i-1][j-1] == false){
                    grid[i-1][j-1] = true;
                }
            }
        }
    }

    for (int i = grid.size() - 5; i >= 0; i--) {        
        for (int j = grid[0].size()-5; j >= 0; j--) {
            if(grid[i][j] == true){
                if(grid[i][j+1] == false){
                    grid[i][j+1] = true;
                }
                if(grid[i+1][j] == false){
                    grid[i+1][j] = true;
                }
                if(grid[i+1][j+1] == false){
                    grid[i+1][j+1] = true;
                }
            }
        }
    }




}

void printGridToFile() {
    ofstream gridFile;
    gridFile.open("grid_inflate.txt");

    for (int i = grid.size() - 1; i >= 0; i--) {        
        for (int j = 0; j < grid[0].size(); j++) {
        gridFile << (grid[i][j] ? "1" : "0");           
        }
        gridFile << endl;
    }
    gridFile.close();
}