Triple Pointers in Programming

In various programming languages, pointers serve as powerful tools for memory management and indirection. However, when does the need arise for multiple levels of pointer dereferencing, leading to constructions like triple pointers (char***)?

Purpose and Advantages of Triple Pointers

While regular pointers (char*) hold the address of a variable, a triple pointer represents a situation where:

• char**foo points to a pointer that itself points to a pointer
• char***foo points to the pointer that points to the previous pointer, and ultimately to a character value

One practical application of triple pointers arises in scenarios where hierarchical data structures or objects are involved. Consider the following code snippet:

struct invocation {
    char* command;
    char* path;
    char** env;
};

This structure defines an invocation object that encapsulates various details of a subprocess, including its command, path, and environment variables (env). To manage these objects, a separate function might be employed:

void browse_env(size_t envc, char*** env_list);

In this case, the browse_env function accepts a list of environment variable arrays, each represented by a triple pointer (char***env_list). This allows the function to traverse the nested hierarchy of pointers and access the character values corresponding to each environment variable.

By employing triple pointers, programming constructs can effectively work with multi-level data structures, facilitating complex data manipulation and processing tasks.