Question

#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;

//Function Prototypes ***************************
bool openFile(fstream &inFile);
void validateFileData(fstream &inFile, int& numRows, int& numCols);
double getGrayValue(fstream &inFile, int numRows, int numCols);

/************************************************
***************************** M A I N  **********
************************************************/
int main() {
//Var Dictionary ****************************
int numRows, numCols;   //size of our ppm image
bool isGoodFile;        //tells if file opened OK
double grayValue;       //grayscale: avg of all pixels in img
fstream inFile;         //file holding ppm image

//1.0 Init
isGoodFile = openFile(inFile);

//2.0 Process File **************************
if (isGoodFile) {//we have a file to process
    validateFileData(inFile, numRows, numCols);

    if ( (numRows>0) && (numCols>0) ) {//we have proper PPM file
        grayValue = getGrayValue(inFile, numRows, numCols);
        cout << "\nThe average value for this image is: " <<  grayValue << endl;
    } else //file did not match PPM spec's
        cout<<"The file was not in proper ASCII PPM format\n\n";

}//isGoodFile
else //file failed to open properly
    cout<<"File failed to open correctly\n";

//3.0 Finish up *****************************
inFile.close(); //must always CLOSE all files we open
cout<<"\n\n\n\t<<< Normal Termination >>>\n\n";
    return 0;
    }

/************************************************
***************************** openFile **********
************************************************/
bool openFile (fstream &inFile) {
//Receives fstream input file
//Prompts user for path/name & attempts to open file
//Returns T/F if open succeeded or not

//var dictionary
char fileName[80];  //path & name of PPM file

//1.0) Prompt user & get filename
cout<<"\nPlease enter the name of your PPM file: ";
cin.getline(fileName,80);
cout<<"\nFile name is: "<< fileName << endl; //data echo

//2.0) Attempt to open file
inFile.open(fileName);

return (inFile.good()); //true if file OK
}//openFile

/************************************************
***************************** validateFileData **
************************************************/
void validateFileData(fstream &inFile, int& numRows, int& numCols){
//Receives fstream input file (already opened)
//Processes (and verifies) file is ASCII PPM format
//Returns with numCols (width) and numRows (height) of image
//   and the file pointer at the first pixel of file
//   If file is not in PPM format, will print errMsg
//   and return -1 for numRows/numCols.

//var dictionary
int width, height, maxColor;    //PPM characteristics
bool isGoodPPM = true;          //flag for our tests
char myLine[80];                //lines of PPM file (text)

//1.0) Test 1st line: "P3"
cout<<"\nData echo of file input:\n";
inFile.getline(myLine, 80); //grab whole 1st line
cout<<myLine<<endl;         //echo it back to human

if ( (myLine[0]!='P') || (myLine[1]!='3') ) //test it
    isGoodPPM = false;  //we have bad file

//2.0 Test 2nd line (if needed): "# any old comment"
if (isGoodPPM) {//keep testing ONLY if file still alive
    inFile.getline(myLine,80);  //grab whole 2nd line
    cout<<myLine<<endl;         //echo it back to human

    if (myLine[0]!='#') //test for comment
        isGoodPPM = false;  //bad file
}

//3.0 Test 3rd & 4th lines: "<width> <height> <255>
if (isGoodPPM) {
    inFile >> width >> height >> maxColor;  //grab 3 integers 
    cout << width << " " << height << endl  //echo back
        << maxColor << endl;

    //test our numbers
    if ( (width<=0) || (height<=0) || (maxColor!=255) )
        isGoodPPM = false;  //bad file
}

//4.0 Return results
if (isGoodPPM) { //file passed inspection
    numCols = width;  numRows = height; 
} else {
    numCols = numRows = -1; //bad file
}

}//validateFileData

/************************************************
***************************** getAvgPixel *******
************************************************/
double getGrayValue(fstream &inFile, int numRows, int numCols){
//Receives fstream input file, with pointer at first pixel value
//         and the numRows (height) and numCols (width) of image
//Reads all pixels (RGB Values) 
//Returns the average (double) of all the pixels (grayScale value)

double average = 0.0; //variable to return the average
const int MAXROW = numRows;//variable for max amount of rows, added one so i could use it in a loop better
const int MAXCOL = numCols;//variable for max amount of rows, added one so i could use it in a loop better
char myLine[80];//set up array to store the values in
int temp=0;//variable to temporarily store numbers in
int adding=0;//variable to store the added numbers in
int total=0;//variable to store the total amount of numbers in
int column=0;//variable to store column position
int row=0;//variable to store column position
const int MYLINEMAX =81;

inFile.getline(myLine, 80);
while((column<MAXCOL) && (row<MAXROW)){//set up a loop for the row
    for(int i=0;i<MYLINEMAX;i++){
        temp=adding;
        adding=temp+myLine[i];
        total++;
    }
    average=adding/total;
}




return average;
}//getGrayValue

我非常困惑如何在最后一部分做数学，检查工作正常，但我似乎无法做数学，即使我发起'平均'为0我的命令提示中没有打印出来

Answer 1

getGrayFile（）永远不会更改列或行，因此while循环永远不会终止。

从ascii图像获取灰度颜色的平均值

1 个答案: