Easy way converting string to int?

Question

How can i convert a string of number (and i mean string not char ,because the atoi function works for char ,and didn't work for string for me) to an integer . I tried this but it didn't work :

int main(){
int P,W;
string ST1 , ST2;
getline(cin,ST1,' ');
getline(cin,ST2);
P = std::atoi(ST1);
W = std::atoi(ST1);
return 0 ;
}

Greg Hewgill · Accepted Answer · 2013-09-11 23:09:53Z

1

You can call any function taking a const char * with a string using .c_str():

P = std::atoi(ST1.c_str());

answered Sep 11, 2013 at 23:09

Greg Hewgill

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2 Comments

us2012 Over a year ago

Yes, but why do that when there's std::stoi?

Greg Hewgill Over a year ago

@us2012: This technique is generally useful for calling any function that takes const char *, not merely for converting strings to integer. Also, std::stoi is C++11 (and later) only.

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