patterncppModerate
Parsing text file in C++
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textfileparsing
Problem
I have a text file that contains
Text file:
Instead of breaking them into individual strings using the code shown below:
What are some better strategies other than coding it this way?
Side note
I declared all the variables to strings because of the
name, age, salary, hoursWorked, randomText and are filled with different delimiters.Text file:
susan:25-2600,28[asd]
mary:21-2200,38[asd]
john:23-3400,46[asd]Instead of breaking them into individual strings using the code shown below:
string name,age,salary,hoursWorked,randomText;
ifstream readFile("textfile.txt");
while(getline(readFile,line)) {
stringstream iss(line);
getline(iss, name, ':');
getline(iss, age, '-');
getline(iss, salary, ',');
getline(iss, hoursWorked, '[');
getline(iss, randomText, ']');
}
readFile.close();What are some better strategies other than coding it this way?
Side note
I declared all the variables to strings because of the
getline() method.Solution
I would create a class and define an input operator:
Now your code looks like this:
PS. I noticed you were using
Don't explictly
struct Person
{
std::string name;
std::string age;
std::string salary;
std::string hoursWorked;
std::string randomText;
friend std::istream& operator>>(std::istream& str, Person& data)
{
std::string line;
Person tmp;
if (std::getline(str,line))
{
std::stringstream iss(line);
if ( std::getline(iss, tmp.name, ':') &&
std::getline(iss, tmp.age, '-') &&
std::getline(iss, tmp.salary, ',') &&
std::getline(iss, tmp.hoursWorked, '[') &&
std::getline(iss, tmp.randomText, ']'))
{
/* OK: All read operations worked */
data.swap(tmp); // C++03 as this answer was written a long time ago.
}
else
{
// One operation failed.
// So set the state on the main stream
// to indicate failure.
str.setstate(std::ios::failbit);
}
}
return str;
}
void swap(Person& other) throws() // C++03 as this answer was written a long time ago.
{
swap(name, other.name);
swap(age, other.age);
swap(salary, other.salary);
swap(hoursWorked, other.hoursWorked);
swap(randomText, other.randomText)
}
};Now your code looks like this:
Person data;
while(readFile >> data)
{
// Do Stuff
}PS. I noticed you were using
string and ifstream without the std::. This suggests you have using namespace std; in your code. Please don't do that. see Why is “using namespace std;” considered bad practice?Don't explictly
close() a file unless you are going to check that it worked (or are going the re-open). Prefer to let the destructor do the closing (that way it is exception safe). See: My C++ code involving an fstream failed reviewCode Snippets
struct Person
{
std::string name;
std::string age;
std::string salary;
std::string hoursWorked;
std::string randomText;
friend std::istream& operator>>(std::istream& str, Person& data)
{
std::string line;
Person tmp;
if (std::getline(str,line))
{
std::stringstream iss(line);
if ( std::getline(iss, tmp.name, ':') &&
std::getline(iss, tmp.age, '-') &&
std::getline(iss, tmp.salary, ',') &&
std::getline(iss, tmp.hoursWorked, '[') &&
std::getline(iss, tmp.randomText, ']'))
{
/* OK: All read operations worked */
data.swap(tmp); // C++03 as this answer was written a long time ago.
}
else
{
// One operation failed.
// So set the state on the main stream
// to indicate failure.
str.setstate(std::ios::failbit);
}
}
return str;
}
void swap(Person& other) throws() // C++03 as this answer was written a long time ago.
{
swap(name, other.name);
swap(age, other.age);
swap(salary, other.salary);
swap(hoursWorked, other.hoursWorked);
swap(randomText, other.randomText)
}
};Person data;
while(readFile >> data)
{
// Do Stuff
}Context
StackExchange Code Review Q#38879, answer score: 15
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