Is there a way to convert from a string to pure code in C++?

I know that it's possible to read from a .txt file and then convert various parts of that into string, char, and int values, but is it possible to take a string and use it as real code in the program?

Code:

string codeblock1="cout<<This is a test;";
string codeblock2="int array[5]={0,6,6,3,5};}";
int i;
cin>>i;
if(i)
{
    execute(codeblock1);
}
else
{
    execute(codeblock2);
}

Where execute is a function that converts from text to actual code (I don't know if there actually is a function called execute, I'm using it for the purpose of my example).

You can create a function and parse whatever strings you like and create a data structure from it. This is known as a parse tree. Subsequently you can examine your parse tree and generate the necessary dynamic structures to perform the logic therin. The parse tree is subsequently converted into a runtime representation that is executed.

All compilers do exactly this. They take your code and they produce machine code based on this. In your particular case you want a language to write code for itself. Normally this is done in the context of a code generator and it is part of a larger build process. If you write a program to parse your language (consider flex and bison for this operation) that generates code you can achieve the results you desire.