Question

How to copy the last N characters from a string to the beginning of the string in C

Answer 1

#include <stdio.h>
#include <string.h>

int main()
{
    char str[] = "1234567890";
    int N = 3;

    // sizeof(str) = 11 // 10 + null

    // void* memmove( void* dest, const void* src, std::size_t count )

    memmove(str, str + (sizeof(str) - 1 - N), N); // copies from [7, 8, 9] to [0, 1, 2]

    printf("%s\n", str);
    
    return 0;
}



/*
run:
       
8904567890
    
*/

 

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