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问题描述
首先，谢谢大家的帮助！
First, thank for you all your help!
我遇到的错误是：
我发现问题在于此行：
str.replace(str.find(sought), sought.size(), replacement);
它位于以下过程中：
void DisplayMessages() {
ifstream myReadFile;
string str;
static string myMessages[10];
static int i; // of course my famous i
static int MyPosition;
string sought;
string replacement;
myReadFile.open("C:\\Documents and Settings\\agerho000\\Desktop\\cms_export_test\\outages.htm",ios::in);
i = 0; //the start of my array
sought = "</td>"; // value that I want to replace with nothing
replacement.clear();
if(!myReadFile) // is there any error?
{
cout << "Error opening the file! Aborting…\n";
exit(1);
}
if (myReadFile.is_open())
{
cout << endl;
while (!myReadFile.eof())
{
getline(myReadFile, str);
if (str == "<tr>")
{
myReadFile.seekg(4,ios::cur);
getline(myReadFile, str);
str.replace(str.find(sought), sought.size(), replacement);
cout << str;
myMessages[i]=str;
i++;
}
}
}
i=0;
while (i < 10)
{
cout << i << ") " << myMessages[i] << endl;
i++;
if (myMessages[i]=="")
{
break;
}
}
myReadFile.close();
mainMenu();
}
整个cpp文件显示在下面：
The whole cpp file is displayed below:
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
void mainMenu();
void DisplayMessages();
void AddMessage();
void DeleteMessage();
void EditMessage();
void RunTests();
void CheckFile();
void CreateHtmlFile(string myMessages[10]);
/*
#define MIN 1
#define MAX 100
#define TRUE 1
#define FALSE 0
*/
int main() {
cout << endl;
cout << endl;
cout << "Hello Andrew.\n";
cout << "First you need some sort of menu.\n";
mainMenu();
return 0;
}
void mainMenu() {
int Command;
cout << endl;
cout << endl;
cout << endl;
cout << "What would you like to do?\n";
// cout << "1) Check that tests work!\n";
// cout << "2) Check that the file exists\n";
cout << "3) Display Messages\n";
// cout << "4) Edit a message\n";
// cout << "5) Add a message\n";
// cout << "6) Delete a message\n";
cout << "7) Exit\n";
cout << "Enter a number: ";
cin >> Command;
if (Command == 3)
{
DisplayMessages();
}
if (Command == 7)
{
cout << "Exiting...";
exit(EXIT_SUCCESS);
}
if (Command == 6)
{
DisplayMessages();
}
}
void DisplayMessages() {
ifstream myReadFile;
string str;
static string myMessages[10];
static int i; // of course my famous i
static int MyPosition;
string sought;
string replacement;
myReadFile.open("C:\\Documents and Settings\\agerho000\\Desktop\\cms_export_test\\outages.htm",ios::in);
i = 0; //the start of my array
sought = "</td>"; // value that I want to replace with nothing
replacement.clear();
if(!myReadFile) // is there any error?
{
cout << "Error opening the file! Aborting…\n";
exit(1);
}
if (myReadFile.is_open())
{
cout << endl;
while (!myReadFile.eof())
{
getline(myReadFile, str);
if (str == "<tr>")
{
myReadFile.seekg(4,ios::cur);
getline(myReadFile, str);
str.replace(str.find(sought), sought.size(), replacement);
cout << str;
myMessages[i]=str;
i++;
}
}
}
i=0;
while (i < 10)
{
cout << i << ") " << myMessages[i] << endl;
i++;
if (myMessages[i]=="")
{
break;
}
}
myReadFile.close();
mainMenu();
}
void AddMessage() {
}
/*
void DeleteMessage() {
ifstream myReadFile;
string str;
static string myMessages[10];
static int i; // of course my famous i
static int MyPosition;
string sought;
string replacement;
static int Command;
myReadFile.open("C:\\Documents and Settings\\agerho000\\Desktop\\cms_export_test\\outages.htm",ios::in);
i = 0; //the start of my array
sought = "</b></td>"; // value that I want to replace with nothing
replacement.clear();
if(!myReadFile) // is there any error?
{
cout << "Error opening the file! Aborting…\n";
exit(1);
}
if (myReadFile.is_open())
{
cout << endl;
while (!myReadFile.eof())
{
getline(myReadFile, str);
if (str == "<tr>")
{
myReadFile.seekg(7,ios::cur);
getline(myReadFile, str);
str.replace(str.find(sought), sought.size(), replacement);
myMessages[i]=str;
i++;
}
}
}
i=0;
while (i < 10)
{
cout << i << ") " << myMessages[i] << endl;
i++;
if (myMessages[i]=="")
{
break;
}
}
myReadFile.close();
cout << "Enter the number of the message you would like to delete?\n";
cout << "Or enter 11 to go back to the main menu.\n";
cin >> Command;
while (Command >= 12)
{
cout << "Invalid number, try again!\n";
cout << endl;
cout << "Enter the number of the message you would like to delete?\n";
cout << "Or enter 11 to go back to the main menu.\n";
cin >> Command;
}
if (Command == 11)
{
mainMenu();
}
myMessages[Command].clear();
//clear the string
//now rebuild the htm file with the new array
CreateHtmlFile(myMessages);
}
void EditMessage() {
}
void RunTests() {
}
void CheckFile() {
}
void CreateHtmlFile(string myMessages[])
{
}
//File.seekg(-5); moves the inside pointer 5 characters back
//File.seekg(40); moves the inside pointer 40 characters forward
//tellg() Returns an int type, that shows the current position of the inside-pointer for reading
//tellp() same as above but for writing
//seekp() just like seekg() but for writing
*/
推荐答案
str.replace（str.find（sought），寻求.size（），replacement）; 错误，当 str.find（）找不到要查找的内容时。 str.find（）将返回 str :: npos ，它将不是字符串中的有效位置。因此，替换调用失败，并且出现索引超出范围异常。
str.replace(str.find(sought), sought.size(), replacement); is wrong when str.find() doesn't find what it's looking for. str.find() will return str::npos, which will not be a valid location in the string. Hence, the call to replace fails with the index out of range exception you're seeing.
将其更改为：
std::size_t foundIndex = str.find(sought);
if (foundIndex != str.npos)
str.replace(foundIndex, sought.size(), replacement);
else
std::cout << "Oops.. didn't find " << sought << std::endl;
，并告诉我们是否有帮助。
and let us know if that helps you.
编辑：您可能还想考虑使用字符串算法库
You might also want to consider using boost::algorithm::replace_all from the Boost String Algorithms Library
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