从字符串中提取正确的值

Question

   int a = 10;
   int b = 5;
   char test[]= "bread";

   a = a + test[0];

   cout << a << endl;

Basically i want to use the value of the integer b. In this example the first char of the string is a 'b' so i want to use the value of b and not the ascii value.

I tried casting it like this but did not work.

 a = a + (int)test[0];

The cout should be 15;

Answer 1

Variable names don't exist at runtime. You could use a std::map (or std::unordered_map ) to associate names with values. Simple example:

std::map<char, int> variables;

variables['a'] = 10;
variables['b'] = 5;
std::string test = "bread"; // In C++ prefer std::string over char[]

variables['a'] = variables['a'] + variables[test[0]];

cout << variables['a'] << endl; // Prints 15

Answer 2

The feature you want can only be properly supported in a very dynamic language, like python or tcl. C++ is a compile time language, it has no idea about what your variable b's name means, to the compiler it's just some random symbol. You might change b to abcde, and compiler won't care less.

Once you gave up on the variable name, there is still something that can do.

std::map<char, int> some_map;
some_map['b'] = 5;
char test[]= "bread";
int a = 10;
a += some_map[test[0]];
cout << "a = " << a << endl;