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Parse (split) a string in C++ using string delimiter (standard C++)

Submitted by: @import:stackoverflow-api··
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parsestandardsplitusingdelimiterstring

Problem

I am parsing a string in C++ using the following:

using namespace std;

string parsed,input="text to be parsed";
stringstream input_stringstream(input);

if (getline(input_stringstream,parsed,' '))
{
     // do some processing.
}


Parsing with a single char delimiter is fine. But what if I want to use a string as delimiter.

Example: I want to split:

scott>=tiger


with >= as delimiter so that I can get scott and tiger.

Solution

You can use the std::string::find() function to find the position of your string delimiter, then use std::string::substr() to get a token.

Example:

std::string s = "scott>=tiger";
std::string delimiter = ">=";
std::string token = s.substr(0, s.find(delimiter)); // token is "scott"


-
The find(const string& str, size_t pos = 0) function returns the position of the first occurrence of str in the string, or npos if the string is not found.

-
The substr(size_t pos = 0, size_t n = npos) function returns a substring of the object, starting at position pos and of length npos.

If you have multiple delimiters, after you have extracted one token, you can remove it (delimiter included) to proceed with subsequent extractions (if you want to preserve the original string, just use s = s.substr(pos + delimiter.length());):

s.erase(0, s.find(delimiter) + delimiter.length());


This way you can easily loop to get each token.
Complete Example

std::vector split(const std::string& s, const std::string& delimiter) {
    std::vector tokens;
    size_t pos = 0;
    std::string token;
    while ((pos = s.find(delimiter)) != std::string::npos) {
        token = s.substr(0, pos);
        tokens.push_back(token);
        s.erase(0, pos + delimiter.length());
    }
    tokens.push_back(s);

    return tokens;
}

std::string s = "scott>=tiger>=mushroom";
std::string delimiter = ">=";

split(s, delimiter); // ["scott", "tiger", "mushroom"]

Code Snippets

std::string s = "scott>=tiger";
std::string delimiter = ">=";
std::string token = s.substr(0, s.find(delimiter)); // token is "scott"
s.erase(0, s.find(delimiter) + delimiter.length());
std::vector<std::string> split(const std::string& s, const std::string& delimiter) {
    std::vector<std::string> tokens;
    size_t pos = 0;
    std::string token;
    while ((pos = s.find(delimiter)) != std::string::npos) {
        token = s.substr(0, pos);
        tokens.push_back(token);
        s.erase(0, pos + delimiter.length());
    }
    tokens.push_back(s);

    return tokens;
}

std::string s = "scott>=tiger>=mushroom";
std::string delimiter = ">=";

split(s, delimiter); // ["scott", "tiger", "mushroom"]

Context

Stack Overflow Q#14265581, score: 1030

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