学习C语言遇指针理解障碍，求代码片段指针部分解析

Hey there! Since you're learning C and trying to unpack that pointer-based character copy code your friend sent, let's break this down clearly. You're spot-on that the code is almost certainly copying i characters from arg to targ—let's walk through how the pointers make this work, using a common implementation of this logic as an example.

Example Code Snippet #

First, here's a typical version of the code you're looking at:

void copy_chars(char *targ, const char *arg, int i) {
    // Loop until we've copied all i characters
    while (i > 0) {
        *targ = *arg;  // Copy the current character from source to target
        targ++;        // Move target pointer to the next memory position
        arg++;         // Move source pointer to the next memory position
        i--;
    }
}

Key Pointer Concepts Explained #

Let's break down each pointer-related part step by step:

• Dereferencing with *:
  The * operator here is how we access the value stored at the memory address the pointer points to. So *arg grabs the character that arg is currently pointing to, and *targ = *arg copies that character into the memory location targ references. Think of pointers as "address labels"—* tells you "what's inside the box at this address".

• Incrementing pointers (targ++, arg++):
  When you increment a pointer, it doesn't just add 1 to the raw memory address. It adds the size of the data type the pointer is for. For char* (which points to 1-byte char values), each increment moves the pointer 1 byte forward—perfect for stepping through each character in a string or array. If this were an int* pointer, incrementing would jump 4 bytes (on most systems) to the next integer value.

• Why pointers are useful here:
  Using pointers lets you directly traverse memory without tracking an index variable (like j in targ[j] = arg[j]). It's often more efficient, and it gives you low-level control over how you move through the data—super handy in C for memory manipulation tasks.

Quick Edge Case Note #

If your friend's code includes extra checks (like verifying targ and arg aren't NULL, or stopping early if a null terminator is hit), the core pointer logic still holds. The main idea is using pointers to read from the source, write to the target, and progress through both buffers one character at a time until i copies are done.

内容的提问来源于stack exchange，提问作者Sugoiboy