c++ - ofstream 创建一个文件但不能写入它

Question

修订:这是我的整个可编译程序。它是菜单驱动的，但我坚持的部分是选项 DECRYPT，用于解密 caesar 加密文件，或数字 5(可以在初始问题中输入，解密可以是小写、大写或驼峰案件)。 ofstream 变量 outFile 创建一个由用户命名的文件(必须是一个不存在的文件)。问题是它只创建空文件，并没有将任何数据打印到其中。所有变量都存储正确的值。 cout 有效，但 outFile 无效。有什么我做的不正确吗？我已经尝试测试 bad、fail 和 is_open，但都没有遇到任何问题。我认为文件权限也不会阻止任何事情，因为程序中的其他选项可以很好地创建和写入文件。谁能帮帮我？

#include <iostream>
#include <fstream>
#include <string>
#include <cctype>
#include <map>
#include <iomanip>
#include <vector>
using namespace std;
int main() {
string inputFileName, outputFileName, inData, outData, inWord, outWord, trash;
ifstream inFile, testStream;
ofstream outFile;
bool outPutOpened = false, isLowerCase = false;
char outChar, inChar; 
int shiftNum = 0, idx = 0, total = 0, max = 0, shiftValue = 0;
map<char,int> charMap; 
map<char,int>::iterator mapIt; 
vector<char> alphabet(26); 
vector<char>::iterator shiftIt;
do  {
    inWord.clear();
    outWord.clear();
    cout << "Available options: " << endl;
    cout << "1. ENCRYPT - Encrypt a file using Caesar Cypher" << endl
        << "2. CHARFREQ - display character frequency table for file" 
        << endl << "3. Quit - Exit the program" << endl 
    << "5. DECRYPT - decrypt a cyphered file" << endl << endl;
    cout << "   Enter keyword or option index: ";
    getline(cin, inWord);
    outWord.resize(inWord.length());
    transform(inWord.begin(), inWord.end(), outWord.begin(), ::toupper); 
    if (outWord.compare("ENCRYPT") == 0 || outWord.compare("1") == 0) {
        cout << "CAESAR CYPHER PROGRAM" << endl
        << "======================" << endl << endl;
        do {                
            cout << "Provide the input file name: ";

            getline(cin, inputFileName);

            inFile.open(inputFileName.c_str());
            if (inFile.fail()) {
                cout << "Cannot open file, please try again!" << endl;
                inFile.clear();
            }
        }
        while (!inFile.is_open());

        do {
            cout << "Provide the output file name: ";
            cin >> outputFileName;
            getline(cin, trash);                
            testStream.clear();
            testStream.open(outputFileName.c_str());
            if(testStream.good()) {
                cout << "That file already exists, choose another" << endl;
                testStream.clear();
                testStream.close();
            }
            else {
                testStream.clear();
                testStream.close();
                outFile.open(outputFileName.c_str());
                if (outFile.good()) {
                    outPutOpened = true;
                }   
            }
        }
        while (!outPutOpened); 
        cout << "Enter the shift number: ";
        cin >> shiftNum;
        getline(cin, trash );
        while(getline(inFile, inData)) {

        for (idx = 0; idx <= inData.length() - 1; idx++) {
            if  (inData[idx] >= 'a' && inData[idx] <= 'z') {
                outChar = (((inData[idx] - 'a') + shiftNum) % 26) + 'a';
                outFile.put(outChar);
            }
            else if (inData[idx] >= 'A' && inData[idx] <= 'Z'){
                outChar = (((inData[idx] - 'A') + shiftNum) % 26) + 'A'; 
                outFile.put(outChar);
            }
            else {
                outFile.put(inData[idx]);
            }
        }
        }
        inFile.clear();
        inFile.close();
        outFile.clear();
        outFile.close();
    }
    else if (outWord.compare("2") == 0 || outWord.compare("CHARFREQ") == 0){
        cout << "Enter input file name: ";
        getline(cin, inputFileName);
        inFile.open(inputFileName.c_str());
        while (inFile.get(inChar)) {
            if (charMap.find(inChar) == charMap.end()) {
                charMap[inChar] = 1 ;
            }
            else {
                ++charMap[inChar];
            }
        }
        cout << "Character Frequencies For \"" << inputFileName << "\"" 
            << endl;
        for (mapIt = charMap.begin(); mapIt != charMap.end(); mapIt++) {
            total += (*mapIt).second;
        }
        cout << "Total bytes read: " << total << endl;
        for (mapIt = charMap.begin(); mapIt != charMap.end(); mapIt++) {
            cout << " ('" << (*mapIt).first << "') occurs " 
            << (*mapIt).second << " times (" 
            << static_cast<double> ((*mapIt).second) 
            / static_cast<double> (total) << "% of all characters)" << endl;
        }
        inFile.clear();
        inFile.close();
    }
    else if (outWord.compare("5") == 0|| outWord.compare("DECRYPT") == 0) {
        outPutOpened = false;
        do {                
            cout << "Provide the input file name: ";

            getline(cin, inputFileName);

            inFile.open(inputFileName.c_str());
            if (inFile.fail()) {
                cout << "Cannot open file, please try again!" << endl;
                inFile.clear();
            }
        }
        while (!inFile.is_open());          
        while (inFile.get(inChar)) {
            if (inChar < 'a' || inChar > 'z') {
                inFile.ignore();
            }
            else {
                inChar -= 'a'; 
                alphabet[static_cast<int> (inChar)]++;
            }
        }
        for (idx = 0; idx < alphabet.size(); idx++) {
            if(max < alphabet[idx]){
                max = alphabet[idx];
            }
        }
        shiftIt = find(alphabet.begin(), alphabet.end(), max);

        shiftValue = (distance(alphabet.begin(), shiftIt) - 4);
        if (shiftValue < 0) {
            shiftValue += 26;
        }
        inFile.close();
        do {                
            inFile.open(inputFileName.c_str());
            if (inFile.fail()) {
                cout << "Cannot open file, please try again!" << endl;
                inFile.clear();
            }
        }
        while (!inFile.is_open());

        outPutOpened = false;
        do {
            cout << "Provide the output file name: ";
            cin >> outputFileName;
            getline(cin, trash);                
            testStream.clear();
            testStream.open(outputFileName.c_str());
            if(testStream.good()) {
                cout << "That file already exists, choose another" << endl;
                testStream.clear();
                testStream.close();
            }
            else {
                testStream.clear();
                testStream.close();
                outFile.open(outputFileName.c_str());
                if (!outFile.good()) {
                    cout << "bad output"<< endl;
                    outFile.clear();
                }   
                if (outFile.good()) {
                    outPutOpened = true;
                }
            }
        }
        while(!outPutOpened); 

        while((inFile.get(inChar))) {

            if  (inChar >= 'a' && inChar <= 'z') {


                inChar -= shiftValue;
                if (inChar < 'a') {
                    inChar += 26;
                }

            outFile << inChar;
            }
            else if (inChar >= 'A' && inChar <= 'Z'){
                inChar -= shiftValue;
                if (inChar < 'A') {
                    inChar += 26;
                }
                outFile << inChar;   

            }
            else {
                outFile << inChar;
            }

        }
    }
    else if (outWord.compare("3") == 0 || outWord.compare("QUIT") == 0) {
        break;
    }
    else {
        cout << inWord << " is an unrecognized option, please try again" 
        << endl;
    }
}
while (outWord.compare("3") || outWord.compare("QUIT")); 
return 0;

Answer 1

为了将字符实际写入文件，您必须刷新流。在 write-to-outFile-while 循环之后执行:

outFile.flush();

.. 文本将被很好地写入文件。