5 lab C

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    const int SIZE = 40;
    char s[SIZE][80];
    char *p[SIZE], *temp;
    FILE *fp;
    int i, j, n = 0;
    fp = fopen("data.txt", "rt");
    if (fp == NULL) {
        printf("\nCan't open file to read!");
        exit(1);
    }
    while (1) {
        fscanf(fp, "%s", &s[n][0]);
        p[n] = &s[n][0]; n++;
        if (feof(fp) || n> SIZE - 1) break;
    }
    i = 0;
    while ( i < n-1) {
//      printf("%s ",  p[i+1]);
//          printf("%s ",  p[i]);
temp = p[i+1];
p[i+1] = p[i];
p[i] = temp;
printf("%s ",  p[i]);
printf("%s ",  p[i+1]);
            i++;
            i++;
    }

    fclose(fp);
    fp = fopen("res01.txt", "wt");
    if (fp == NULL) {
        printf("\nCan't open file to write!");
        exit(1);
    }
    for (i = 0; i<n; i++) fprintf(fp, "%s\n", p[i]);
    fclose(fp);
    fflush(stdin); getchar(); return 0;
}