הפוך מקוון מחרוזת

i do this program

#include <stdio.h>#include <stdlib.h>#include <string.h>int main(){    char *str, c;    int x = 0, y = 1;    str = (char*)malloc(sizeof(char));    printf("Inserisci stringa principale : ");        while (c != '\n') {        // read the input from keyboard standard input        c = getc(stdin);        // re-allocate (resize) memory for character read to be stored        str = (char*)realloc(str, y * sizeof(char));        // store read character by making pointer point to c        str[x] = c;        x++;        y++;        }    str[x] = '\0'; // at the end append null character to mark end of string    printf("\nLa stringa inserita : %s", str);      char *sub, b;      int w = 0, z = 1;      sub = (char*)malloc(sizeof(char));      printf("Immetti sottostringa da cercare : ");          while (b != '\n') {            // read the input from keyboard standard input            b = getc(stdin);            // re-allocate (resize) memory for character read to be stored            sub = (char*)realloc(sub, z * sizeof(char));            // store read character by making pointer point to c            sub[w] = b;            w++;            z++;          }      sub[w] = '\0'; // at the end append null character to mark end of string    char *p1, *p2, *p3;    int i=0,j=0,flag=0, occurrences=0;      p1 = str;      p2 = sub;      for(i = 0+1; i<strlen(str); i++)      {        if(*p1 == *p2)          {              p3 = p1;              for(j = 0;j<strlen(sub);j++)              {                if(*p3 == *p2)                {                  p3++;p2++;                }                 else                  break;              }              p2 = sub;              if(j + 1 == strlen(sub))              {                 flag = 1;                 occurrences = occurrences + 1;                printf("\nnel numero di volte : %d\n",occurrences );                printf("\nSottostringa trovata all'indice : %d\n",i );              }          }        p1++;       }      if(flag==0)      {           printf("Sottostringa non trovata");      }    free(str);    free(sub);    return (0);    }

Which searches for a given substring in a string, once it finds print the locations where the substring is found and the number of times it is found, at present for example if my string is aaooaaoo and my substring or output outputs the positions , 3 and 7 and last 2 (ie the number of occurrences) I would need to get first 2 and then the positions in reverse order, ie in this case should print next to the 2nd before the 7 and then the 3, How could you do it?

I came across a strange Codecademy exercise that required a function that would take a string as input and return it in reverse order. The only problem was you could not use the reversed method or the common answer here on stackoverflow, [::-1].

Obviously in the real world of programming, one would most likely go with the extended slice method, or even using the reversed function but perhaps there is some case where this would not work?

I present a solution below in Q&A style, in case it is helpful for people in the future.

How do you reverse a string in place (or in-place) in JavaScript when passed to a function with a return statement? All without using the built-in functions? .reverse(), .charAt(), etc.

How can we reverse a simple string in Go?

#include <stdio.h>#include <string.h>void print_reverse(char *s){    size_t len = strlen(s);    char *t = s + len - 1;    while (t >= s)    {        printf("%c", *t);        t = t - 1;    }    puts("");}

Above is a function that will display a string backward on the screen. But I don't understand the 7th line (char *t = s+ len-1;). Could anybody explain this is spoken English please?