What is the process of converting big endian to little endian in C without the use of library functions?

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The process of converting big endian to little endian in C without the use of library functions involves the following steps:

1. Declare a variable to store the input value in big endian format.
2. Create a pointer and point it to the address of the input variable.
3. Declare another variable to store the output value in little endian format.
4. Create another pointer and point it to the address of the output variable.
5. Use a for loop to iterate through the bytes of the input value starting from the most significant byte (MSB).
6. Copy each byte to the output variable starting from the least significant byte (LSB).
7. Increment the input pointer and decrement the output pointer in each iteration of the loop.
8. After the loop completes, the output variable will contain the same value as the input variable, but in little endian format.

Here is an example code snippet that demonstrates the process:

#include <stdio.h>

int main() {
    uint32_t input = 0x12345678; // input in big endian format
    uint32_t output; // output in little endian format
    uint8_t *inp_ptr = (uint8_t *)&input; // pointer to the input variable
    uint8_t *out_ptr = (uint8_t *)&output + sizeof(output) - 1; // pointer to the output variable

    for (int i = 0; i < sizeof(uint32_t); i++) {
        *out_ptr = *inp_ptr; // copy byte from input to output
        inp_ptr++; // move input pointer to next byte
        out_ptr--; // move output pointer to previous byte
    }

    printf("Input (big endian): %08x\n", input);
    printf("Output (little endian): %08x\n", output);

    return 0;
}

Output:

Input (big endian): 12345678
Output (little endian): 78563412