Calling a Function by Its Name (std::string) in C
In C , the question of calling a function by its name stored in a string has arisen. While a basic approach involving conditional statements is known, simpler alternatives have been sought.
Basic Approach
A straightforward method involves using a series of if-else statements to match the function name with the corresponding function pointer. This approach is illustrated below:
<code class="cpp">int function_1(int i, int j) { return i*j; } int function_2(int i, int j) { return i/j; } int callFunction(int i, int j, string function) { if(function == "function_1") { return function_1(i, j); } else if(function == "function_2") { return function_2(i, j); } ... return function_1(i, j); }</code>
Proposed Alternative
The new approach aims to simplify the calling process by utilizing an std::map to map function names to function pointers. For functions with identical prototypes, this technique can provide a more concise solution:
<code class="cpp">#include <map> typedef int (*FnPtr)(int, int); int add(int i, int j) { return i+j; } int sub(int i, int j) { return i-j; } int main() { std::map<:string fnptr> myMap; myMap["add"] = add; myMap["sub"] = sub; std::string s("add"); int res = myMap[s](2,3); std::cout <p>This approach utilizes the myMap[s](2,3) syntax, which retrieves the function pointer mapped to the string s and invokes the corresponding function with the provided arguments. The example shown calculates and outputs 5 as the result of the "add" function call.</p></:string></map></code>
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