C++: Get numbers between two string delimiters and values after extracting desired integer from string using stringstream - getline

Question

```
#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <fstream>
using namespace std;
bool findCurrentNumber (int currentNumber, int foundNumber)
{
if (currentNumber == foundNumber)
{
return true;
}
return false;
}
int main()
{
ifstream inputFile;
inputFile.open("C:\\Projects\\data.txt");
if (!inputFile)
{
cerr << "Error reading file ";
}
else
{
int searchCurrentNumber;
cout << "Please type in the number you are looking for: ";
cin >> searchCurrentNumber;
bool foundRelevantSection = false;
string delimiter = "energy";
size_t pos = 0;
string token;
string line;
while (getline(inputFile, line))
{
while ((pos = line.find(delimiter)) != string::npos)
{
token = line.substr(0, pos);
//check the found token
//cout << token << endl;
line.erase(0, pos + delimiter.length());
stringstream ss;
//store the whole string into stringstream
ss << token;
string temp;
int found;
while (!ss.eof())
{
//extract the word by word from stream
ss >> temp;
//Check the given word is integer or not
if (stringstream(temp) >> found)
cout << "Number found: " << found << " " << endl;;
//no space at the end of string
temp = "";
}
if (findCurrentNumber (searchCurrentNumber, found) == true)
{
while (getline (inputFile, line))
{
if (foundRelevantSection)
{
//if no matches were found, the function returns "string::npos"
if(line.find("total") != string::npos)
{
//relevant section ends now
foundRelevantSection = false;
}
else
{
cout << line << endl;
}
}
else
{
if (line.find("point") != string::npos )
{
foundRelevantSection = true;
}
}
}
}
else
{
cout << "The number is not equal on this line compared to what is typed in!" << endl;
}
}
} //closes the while-loop
} //closes the if/else-statement
inputFile.close();
return 0;
}
```
Hi all,
I would like to parse an input file having this format:
point 152 # energy # 0.5
152 152 152 152 152 152
152 152 152 152 152 152
total 0.011 0.049 0.035
point 153 # energy # 1.5
153 153 153 153 153 153
153 153 153 153 153 153
total 0.015 0.050 0.040
The code accepts an user-supplied integer and compares it to the number extracted from e.g. the string "point 152 # energy". If the user enters the number "152", the code should give following numbers:
output:
152 152 152 152 152 152
152 152 152 152 152 152
Unfortunately, my code returns exactly the opposite if number 152 is entered or if number 153 is entered no values are returned.
Could anyone help me and tell me what I am doing wrong? I am grateful for any hint!
Thanks in advance!
Best wishes,
DaveS

Answer 1

Fix for 2nd bug added at the end.
You should work on getting better with a debugger, I found your problem with one:
while (!ss.eof())
{
//extract the word by word from stream
ss >> temp;
//Check the given word is integer or not
if (stringstream(temp) >> found)
cout << "Number found: " << found << " " << endl;;
//no space at the end of string
temp = "";
}
doesn't stop on finding 152 in "point 152 # ", but goes on to process # which turns found into 0.
This code with a break fixes that part:
while (!ss.eof())
{
//extract the word by word from stream
ss >> temp;
//Check the given word is integer or not
if (stringstream(temp) >> found)
{
cout << "Number found: " << found << " " << endl;
foundRelevantSection = true;
break; /* exits the while now */
}
//no space at the end of string
temp = "";
}
or you could test found in the while, by first setting it to 0, and testing with && found == 0
Then the part calling findCurrentNumber (int currentNumber, int foundNumber) is garbage (or a placeholder for something way more complex?) as if (findCurrentNumber (searchCurrentNumber, found) == true) is simply if (searchCurrentNumber == found) which is much easier to read!
I didn't check if there are more bugs farther down the code, but with the break you definitely get the correct value in found.
part 2
You already found "point", so you shouldn't look for it again!
I added foundRelevantSection in the code above, before break.
Change the next part to (no if relevant, no if point found):
while (getline (inputFile, line) && foundRelevantSection)
{
//if no matches were found, the function returns "string::npos"
if(line.find("total") != string::npos)
{
//relevant section ends now
foundRelevantSection = false;
}
else
{
cout << line << endl;
}
}
hoping it was the last bug...

Answer 2

I checked your code, although isn't straightforward but I was able to understand what you're trying to achieve at least. Anyways, here is my own contribution to your question. I hope it helps you or at least gives you a better view of the solution
#include <iostream>
#include <fstream>
#include <regex>
int main()
{
using namespace std;
ifstream inputFile;
inputFile.open("sample.dat");
if (!inputFile)
{
cerr << "Error reading file ";
}
else
{
int searchCurrentNumber;
bool foundRelevantSection = false;
cout << "Please type in the number you are looking for: ";
cin >> searchCurrentNumber;
//while we are still having data to read
std::string currentLine;
while (std::getline(inputFile, currentLine))
{
//remove the top and bottom section of the log
if((currentLine.find("point") == string::npos) && (currentLine.find("total") == string::npos ))
{
//now all the numbers are in the middle then search for the number
size_t pos = currentLine.find(std::to_string(searchCurrentNumber));
if(pos!= string::npos){
//we found the number so we are in the section hopefully
string line;
while (std::getline(inputFile, line))
{
if (foundRelevantSection)
{
//if no matches were found, the function returns "string::npos"
if(line.find("total") != string::npos)
{
//relevant section ends now
foundRelevantSection = false;
}
else
{
cout << line << endl;
}
}
else
{
if (line.find("point") != string::npos )
{
foundRelevantSection = true;
}
}
}
}
}
}
}
return 0;
}