c++stringcharstdstring

How to convert a std::string to const char* or char*

How can I convert an std::string to a char* or a const char*?

Solution

  • If you just want to pass a std::string to a function that needs const char *, you can use .c_str():

    std::string str;
const char * c = str.c_str();

    And if you need a non-const char *, call .data():

    std::string str;
char * c = str.data();

    .data() was added in C++17. Before that, you can use &str[0].

    Note that if the std::string is const, .data() will return const char * instead, like .c_str().

    The pointer becomes invalid if the string is destroyed or reallocates memory.

    The pointer points to a null-terminated string, and the terminator doesn't count against str.size(). You're not allowed to assign a non-null character to the terminator.