c++ - 获取字符串的最后 9 个字符

Question

你好，需要帮助获取字符串的最后 N 个字符:有这样一行:

PutPixel(x + N, y + N, 0, 0, 0); // N = 1 - 1000

并希望获得最后 9 个符号，女巫是“0, 0, 0”；” ，我有 50k 行，每行都有不同的数字，我想找到每行 0,0,0);最后把它从数组中删除，首先我必须找到它们我试过 line[N].substr(0,-9); 但那没有用，我也试过 line[N].find("0, 0, 0); "); 但这只是给我玩一个很长的数字谎言 "4294967295"

完整代码:

const string file = "putpixel.txt";
const int maxlines = 60000;
int main()
{
    string lines[maxlines];
    fileRead(file,lines);
    deleteBlack(lines);
    cout << lines[0].find("0, 0, 0);");
    return 0;
}

void fileRead(const string fn,string line[]){
    int index = 0;
    ifstream fin(fn.c_str());
    while(!fin.eof()){
        getline(fin,line[index],';');
        index++;
    }
    fin.close();
}

Answer 1

此代码从文件中加载文本并搜索

"0, 0, 0" 并使用 "" 替换它

searchresult = stringFile.find("0, 0, 0") 和

substr( searchresult + search_string.length() , stringFile.length() )

它将一直这样做直到 searchresult = -1。如果是，它将更改的结果写回文件。

#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
using namespace std;


int main(){

    int searchresult=1;
    ifstream inFile;

    // load file into string
    inFile.open("putpixel.txt"); 
    stringstream strStream;
    strStream << inFile.rdbuf(); 
    string stringFile = strStream.str(); 
    inFile.close();

    cout<<"\nBefore replace \n";
    cout<<""<<stringFile<<" \n";


    // initialize search string and replace string
    string search_string = " 0, 0, 0";
    string replace_string = " ";


    // while searchresult is still greater than zero then keep searching
    while ( searchresult > 0 ){

        searchresult = stringFile.find(search_string);

        // if searchresult is greater than zero then keep doing this
        if(searchresult >= 0){
             string tmpstring = stringFile.substr(0,searchresult);
             tmpstring += replace_string;
             tmpstring += stringFile.substr(searchresult+search_string.length(), stringFile.length());
             stringFile = tmpstring;
        }

    }
    // update file after removing
    ofstream outFile("putpixel.txt");
    outFile << stringFile;
    outFile.close();

    cout<<"\nAfter replace \n";
    cout<<""<<stringFile<<" \n";

cout<<"\nPress ANY key to close.\n\n";
cin.ignore(); cin.get();
return 0;
}

putpixel.txt 之前的输出:

PutPixel(x + N, y + N, 0, 0, 0);
PutPixel(x + N, y + N, 0, 0, 0);
PutPixel(x + N, y + N, 0, 0, 0);
PutPixel(x + N, y + N, 0, 0, 0);

putpixel.txt 的输出:

PutPixel(x + N, y + N, );
PutPixel(x + N, y + N, );
PutPixel(x + N, y + N, );
PutPixel(x + N, y + N, );