从新文件中的 output 文件中读取，并比较输出

Question

I need a little bit help with my code. The first part of the code, was easy to create. Read from two textfiles -> Output in a new textfile. My next step is to compare the both outputs line by line.

• If the number is the same, the numbers stays.
• If the number is different to the number of textfile2, the number with be replaced.

Example:

Textfile1:
2221112221
1122221112
2222221111
1111111111

Textfile2:
2222221111
2211222212
1111111111
2221112222

Result that should happen on Textfile3:
(like I'm overlapping textfile2 on textfile1)

2222221111
2211222212
1111111111
2221112222

So I already researched for str.compare , but I'm not able to output the result as above stated. I don't know if this works with it.

if((line2.compare(0, line2.length(), line1)) == 0)

string line1, line2;
ifstream read1, read2;

read1.open("test.txt", ios::in);
read2.open("test2.txt", ios::in);
ofstream outFile("outputfile.txt", ios::out | ios::app);


if(!read1 || !read2){
    cerr << "One file is missing" << endl;
    exit(1);

}

else {
    while(getline(read1, line1))
    {
        outFile << line1;

    }
    while(getline(read2, line2))
    {
        outFile << line2 << endl;
    }

Thanks a lot guys!

Answer 1

iterate the strings and compare character vs. character? This would allow you to achieve what you're looking for.

This example obviously does not have exception handling (eg different string lengths):

std::string corn = "I eat Corn!";
std::string rice = "I eat Rice!";

int main()
{
    for (size_t i = 0; i < corn.length(); i++)
    {
        if (corn[i] != rice[i])
        {
            rice[i] = corn[i];
        }
    }
    std::cout << rice;
}