c++: can I use .find function to look for multiple elements in a string

Question

c++: can I use .find function to look for multiple characters in a string ex: looking for + and - in an array of linear equations

Not clear. Looking for multiple instances of + or -? Or do you want to know when both exist? Next to each other or separate? Give examples of what should pass and what should fail in your search. — Christopher Pisz, Jun 22 '18 at 21:26
I want to cut the equation into terms so i want to look for both of them at the same time can i use the .find function or is there another way? — Rania saleh, Jun 22 '18 at 21:29
If you want to tokenize it you might be better using `std::regex` and friends. — NathanOliver, Jun 22 '18 at 21:32
Possible duplicate of [C++: Extracting symbols/variables of an analytical mathematical expression](https://stackoverflow.com/questions/40997788/c-extracting-symbols-variables-of-an-analytical-mathematical-expression) — Jonathan Mee, Jun 23 '18 at 00:58

f4. · Answer 1 · 2018-06-22T21:37:43.823

One way of doing it:

auto it = std::find_if( str.begin(), str.end(), [](char c){
    return c == '+' || c == '-';
} );

You could also use std::strpbrk, which searches for one or several separators in a string. https://en.cppreference.com/w/cpp/string/byte/strpbrk

As per your comment you want to tokenize the string, std::strtok will do the job:

char *token = std::strtok( input, "+-" );
while( token != nullptr )
{
    token = std::strtok( NULL, "+-" );
}

warning: the above code is not thread safe.

1 Answers1