free(): invalid next size(normal) - c

Question

When running this code with an input .txt file containing somewhere between 200-300 integers (separated by spaces) i get an error right before the for loop with the fprintf statement.
I am not sure if qsort is causing this error or why it occurs but any insight would be appreciated.
(this file is run by adding the name of the input file and the output file in the command line ex: ./program input.txt output.txt
My code:
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
int cmpfunc (const void * a, const void * b)
{
return ( *(int*)a - *(int*)b );
}
int main(int argc, char *argv[]){
if(argc != 3){
printf("\nInvalid input\nPlease provide the input and output text file names as %s name1 name2\n", argv[0]);
}else{
printf("\nPart A: \n");
printf("..............................................................................................................\n\n");
char *fn1 = argv[1]; //variables
char *fn2 = argv[2];
int temp = 0;
int counter = 0;
int index = 0;
int index2 = 0;
int sort = 0;
FILE *fp1 = fopen(fn1, "r"); //read file
FILE *fp2 = fopen(fn2, "w"); //write file
if(fp1 == NULL){ //test if fp1 was opened
printf("There was an error opening the input file");
}
char data[10]; //ints can only hold 10 digits
int *integerArr;
int *tempPointer;
integerArr = malloc(10*sizeof(int));
int sizeOfArrs = 10;
printf("Reading in the textfile: ");
while(fscanf(fp1,"%s",data) != EOF){ //reads in the file breaking on each whitespace and ends at the EOF pointer
temp = strlen(data);
if(temp <=10){
temp = atoi(data);
integerArr[counter] = temp;
printf(".");
counter++;
if(counter == sizeOfArrs -1){
temp = sizeOfArrs * 2;
tempPointer = realloc(integerArr, temp);
if(tempPointer != NULL){
integerArr = tempPointer;
}
}
}else printf("\ninteger had too many digits\n");
}
printf(" Done\n%d Numbers were found\n", counter);
printf("The integers found in the %s file: \n", argv[1]);
index = 0; //reset index to 0;
for(index;index<counter;index++){ //prints the unsorted contents of the file
printf("%d ", integerArr[index]);
}
printf("\n\nPart B\n");
printf("..............................................................................................................\n\n");
printf("The integers found in the %s file after sorting: \n", argv[1]);
qsort(integerArr, counter, sizeof(int), cmpfunc); //best function ever (sorts the array using the cmpfunc to tell if an integer is greater than less than or equal to the next one)
index = 0; //resets the index
for(index; index <counter; index++){ //prints the sorted contents of the file
printf("%d ", integerArr[index]);
fprintf(fp2,"%d ",integerArr[index]); //writes the sorted integers to the new file
}
if(fp2 == NULL){ //tests if the write worked
printf("There was an error writing the outputfile");
}
printf("\n");
close(fp1,fp2); //closes both files
}
return 0;
}

Answer 1

Your fscanf loop is broken. You weren't actually realloc'ing with a larger size. Here's the corrected program [sorry for the pedantic style reedit but you hit one of my nits: long sidebar comments]
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
int
cmpfunc(const void *a, const void *b)
{
return (*(int *) a - *(int *) b);
}
int
main(int argc, char *argv[])
{
if (argc != 3) {
printf("\nInvalid input\nPlease provide the input and output text file names as %s name1 name2\n", argv[0]);
return 1;
}
printf("\nPart A: \n");
printf("..............................................................................................................\n\n");
char *fn1 = argv[1]; // variables
char *fn2 = argv[2];
int temp = 0;
int counter = 0;
int index = 0;
int index2 = 0;
int sort = 0;
FILE *fp1 = fopen(fn1, "r");
FILE *fp2 = fopen(fn2, "w");
// test if fp1 was opened
if (fp1 == NULL) {
printf("There was an error opening the input file");
return 1;
}
// ints can only hold 10 digits
char data[10];
int *integerArr;
int *tempPointer;
int sizeOfArrs = 10;
integerArr = malloc(sizeOfArrs * sizeof(int));
printf("Reading in the textfile: ");
// reads in the file breaking on each whitespace and ends at the EOF
// pointer
while (fscanf(fp1, "%s", data) != EOF) {
temp = strlen(data);
if (temp > 10) {
printf("\ninteger had too many digits\n");
continue;
}
temp = atoi(data);
integerArr[counter] = temp;
printf(".");
counter++;
if (counter == sizeOfArrs - 1) {
sizeOfArrs += 600;
integerArr = realloc(integerArr, sizeOfArrs * sizeof(int));
}
}
// trim array to actual size needed
sizeOfArrs = counter;
integerArr = realloc(integerArr, sizeOfArrs * sizeof(int));
printf(" Done\n%d Numbers were found\n", counter);
printf("The integers found in the %s file: \n", argv[1]);
// prints the unsorted contents of the file
for (index = 0; index < counter; index++) {
printf("%d ", integerArr[index]);
}
printf("\n\nPart B\n");
printf("..............................................................................................................\n\n");
printf("The integers found in the %s file after sorting: \n", argv[1]);
// best function ever (sorts the array using the cmpfunc to tell if an
// integer is greater than less than or equal to the next one)
qsort(integerArr, counter, sizeof(int), cmpfunc);
// prints the sorted contents of the file
for (index = 0; index < counter; index++) {
printf("%d ", integerArr[index]);
// writes the sorted integers to the new file
fprintf(fp2, "%d ", integerArr[index]);
}
// tests if the write worked
if (fp2 == NULL) {
printf("There was an error writing the outputfile");
}
printf("\n");
// closes both files
fclose(fp1);
fclose(fp2);
return 0;
}
Also, note the fclose's at the bottom. There are a few minor bugs left for you to find.