Deprecated conversion from string literal to 'char*'

c++ string char deprecated literals
Matt picture Matt · Mar 10, 2012 · Viewed 47.2k times · Source

I have a program which declares an array of strings like this:

char *colors[4] = {"red", "orange", "yellow", "blue"};

But I get the above compiler warning. It compiles but I'd rather use the non-deprecated way(if there is one). I've tried to find out what it means, but I can't seem to figure it out. I've heard using 'const' before 'char' works, but it would be helpful if someone could explain what the error means. Thanks.

Answer

d_inevitable picture d_inevitable · Mar 10, 2012

The strings that you enter: "red", "organge" etc are "literal", because they are defined inside the program code itself (they are not read directly from disk, user input /stdin etc.).

This means that if at any point you try to write to your colors you will be directly accessing your original input and thus editing it. This would cause some undesired run-time errors.

Declaring it as a const will make sure that you will never try to write to this pointer and such a run-time error can be avoided.

const char *colors[4] = {"red", "orange", "yellow", "blue"};

If you ever feel like editing these values at runtime, then you should copy the strings first.

Related questions

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*?

Read More
std::string to char*

I want to convert a std::string into a char* or char[] data type. std::string str = "string"; char* chr = str; Results in: “error: cannot convert ‘std::string’ to ‘char’ ...”. What methods are there available to do this?

Read More
How to convert a char array to a string?

Converting a C++ string to a char array is pretty straightorward using the c_str function of string and then doing strcpy. However, how to do the opposite? I have a char array like: char arr[ ] = "This is a test"; …

Read More