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Use the C++ streams.

std::string plop("123"); std::stringstream str(plop); int x; str >> x; /* Lets not forget to error checking */ if (!str) { // The conversion failed. // Need to do something here. // Maybe throw an exception } 

PS. This basic principle is how the boost library lexical_cast<> works.

My favorite method is the boost lexical_cast<>

int x = boost::lexical_cast<int>("123"); 

It provides a method to convert between a string and number formats and back again. Underneath it uses a string stream so anything that can be marshaled into a stream and then un-marshaled from a stream (Take a look at the >> and << operators).

Use the C++ streams.

std::string plop("123"); std::stringstream str(plop); int x; str >> x; /* Lets not forget to error checking */ if (!str) { // The conversion failed. // Need to do something here. // Maybe throw an exception } 

PS. This basic principle is how the boost library lexical_cast<> works.

My favorite method is the boost lexical_cast<>

#include <boost/lexical_cast.hpp> int x = boost::lexical_cast<int>("123"); 

It provides a method to convert between a string and number formats and back again. Underneath it uses a string stream so anything that can be marshaled into a stream and then un-marshaled from a stream (Take a look at the >> and << operators).

Use the C++ streams.

std::string plop("123"); std::stringstream str(plop); int x; str >> x; /*  * Lets not forget to error checking   */ if (!str) { // The conversion failed. // Need to do something here. // Maybe throw an exception } 

PS. This basic principle is how the boost library lexical_cast<> works.

This was the original answer I put before the question changed to include the line:

let's assume you don't have boost

My favorite method is the boost lexical_cast<>

int x = boost::lexical_cast<int>("123"); 

It provides a method to convert between a string and number formats and back again. Underneath it uses a string stream so anything that can be marshaled into a stream and then unmarshaled from a stream (Take a look at the >> and << operators).

Use the C++ streams.

std::string plop("123"); std::stringstream str(plop); int x; str >> x; /* Lets not forget to error checking */ if (!str) { // The conversion failed. // Need to do something here. // Maybe throw an exception } 

PS. This basic principle is how the boost library lexical_cast<> works.

My favorite method is the boost lexical_cast<>

int x = boost::lexical_cast<int>("123"); 

It provides a method to convert between a string and number formats and back again. Underneath it uses a string stream so anything that can be marshaled into a stream and then un-marshaled from a stream (Take a look at the >> and << operators).

Thanks for the downvotes. After changing the question on me!

Use the C++ streams.

std::string plop("123"); std::stringstream str(plop); int x; str >> x; /* * Lets not forget to error checking */ if (!str) { // The conversion failed. // Need to do something here. // Maybe throw an exception } 

PS. This basic principle is how the boost library lexical_cast<> works.

This was the original answer I put before the question changed to include the line:

let's assume you don't have boost

My favorite method is the boost lexical_cast<>

int x = boost::lexical_cast<int>("123"); 

It provides a method to convert between a string and number formats and back again. Underneath it uses a string stream so anything that can be marshaled into a stream and then unmarshaled from a stream (Take a look at the >> and << operators).

Use the C++ streams.

std::string plop("123"); std::stringstream str(plop); int x; str >> x; /* * Lets not forget to error checking */ if (!str) { // The conversion failed. // Need to do something here. // Maybe throw an exception } 

PS. This basic principle is how the boost library lexical_cast<> works.

This was the original answer I put before the question changed to include the line:

let's assume you don't have boost

My favorite method is the boost lexical_cast<>

int x = boost::lexical_cast<int>("123"); 

It provides a method to convert between a string and number formats and back again. Underneath it uses a string stream so anything that can be marshaled into a stream and then unmarshaled from a stream (Take a look at the >> and << operators).