尝试将多个输出写入.txt文件C ++

Question

I want to output what is in the inputtwo.h into a txt document. The document is able to be named fine. but when I type in the inputs as asked, the return in the txt is one line of of text but in the wrong format

so say I did two inputs, named it test.txt, then put in "dog cat" as the inputs, then the output in the txt is "dogcatcatdog" where it should be "dog" "cat" "dogcat" "catdog" each should be on their own line in the txt

The following code is my main file

#include <stdio.h>
#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main() 
{
char q1[20];
char q2[20];

int x;

printf("Select number of keywords (integer between 1-10): \n");
scanf("%d", &x);

switch(x){

    case 1:{
        string fileName;
    printf("Input Filename\n");
    cin >> fileName;
    fileName += ".txt";
    ofstream createFile;
    createFile.open(fileName.c_str(), ios::app);

    printf("Input One Keywords: \n");
    scanf("%s", q1);
    createFile << ("%s\n", q1);
    createFile.close();
    return 0;
}
    case 2:{
        string fileName2;
    printf("Input Filename\n");
    cin >> fileName2;
    fileName2 += ".txt";
    ofstream createFile;
    createFile.open(fileName2.c_str(), ios::app);

    printf("Input Two Keywords: \n");
    scanf("%s %s", q1, q2);
#include "inputtwo.h"
    createFile.close();
    return 0;
} 

the include inputtwo.h is

#ifndef INPUTTWO_H
#define INPUTTWO_H

    createFile << ("%s\n", q1);
    createFile << ("%s\n", q2);
    createFile << ("%s" "%s\n", q1, q2);
    createFile << ("%s" "%s\n", q2, q1);

#endif /* INPUTTWO_H */

Answer 1

In inputtwo.h you are writing to file using C++ output (file) stream, which doesn't understand format specifiers in the form of "%s\\n". ("%s\\n", q1) is an expression, where comma , is an operator (see this ). The result of this operator will be q1 and it is written to output stream (file).

The overall result is that you write q1, q2, q1, q2, q2 and q1 without any separators between them.

To fix, stop mixing C and C++ style output. Use C++ style like this:

createFile << q1 << std::endl;
createFile << q2 << std::endl;  
createFile << q1 << " " << q2 << std::endl;
createFile << q2 << " " << q1 << std::endl;

Extending this to the rest of the program one would replace char q1[20]; with std::string q1; (same for q2) and then replace

printf("Input One Keywords: \n");
scanf("%s", q1);

with

std::cout << "Input One Keyword: " << std::endl;
std::cin >> q1;