how to convert a string into integer

[priyanka]

Hi there,

I want to convert a String into integer.

I get the string from a file using :

string argNum;
getline(inputStream,argNum);

I now need to convert argNum into integer.

I tried to use

int a = atoi(argNum);

But I got errot message :error: cannot convert `std::string' to `const
char*' for argument `1' to `int atoi(const char*)'

And for the getline function, the argNum must be a string variable.

Can anyone please tell me how to convert argNum into integer ?

Thank you in advance,
priya

 

[Noah Roberts]

Hi there,

I want to convert a String into integer.

I get the string from a file using :

string argNum;
getline(inputStream,argNum);

Why not:

int x;
inputStream >> x;

I now need to convert argNum into integer.

I tried to use

int a = atoi(argNum);

But I got errot message :error: cannot convert `std::string' to `const
char*' for argument `1' to `int atoi(const char*)'

use c_str() to get the char* insides of a std::string.

 

[red floyd]

use c_str() to get the char* insides of a std::string.

You mean to get the _const_ char* insides of a std::string.

 

[Thomas J. Gritzan]

Hi there,

I want to convert a String into integer.

I get the string from a file using :

string argNum;
getline(inputStream,argNum);

I now need to convert argNum into integer.

I tried to use

int a = atoi(argNum);

But I got errot message :error: cannot convert `std::string' to `const
char*' for argument `1' to `int atoi(const char*)'

And for the getline function, the argNum must be a string variable.

Can anyone please tell me how to convert argNum into integer ?

It's a FAQ:

http://www.parashift.com/c++-faq-lite/
http://www.parashift.com/c++-faq-lite/misc-technical-issues.html#faq-39.2