Function was checked to return value A, but in main, the value was found to be -1

The bug seems to be in binarySearch function and the for-loop it is in. I have placed a few printf to check for values. binarySearch supposed to return value: 8, but index variable in for-loop is -1.

I apologise if the formatting looks terrible. Please give me guidance on how to to post nice looking code here.

Thank you so much!

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

int binarySearch(char[7], char, int, int);
void deleteAndMoveEntry(char[7], int, int);

int main()
// all the variables
const int MAXIMUM = 5000;
char temp[7];
char symbol[MAXIMUM][7];
int sizeSymbol = 0, sizeDeleted = 0;
char toDelete[MAXIMUM][7];
int i = 0, j;
int index;
FILE *in = fopen("stockin.txt", "r");
FILE *deleted = fopen("stockdel.txt", "r");
FILE *out = fopen("stockout.txt", "w");
FILE *errorFile = fopen("error.txt", "w");

while (fscanf(in, "%sn", temp) == 1 && i < MAXIMUM)
strcpy(symbol[i], temp);
i++;
sizeSymbol++;


i = 0;

while (fscanf(deleted, "%sn", temp) == 1 && i < MAXIMUM)
printf("Hin");
strcpy(toDelete[i], temp);
i++;
sizeDeleted++;

// Should we sort array symbol? To implement later for fun

for (i = 0; i < sizeDeleted; i++)
index = binarySearch(symbol, toDelete[i], 0, sizeSymbol);
printf("%dn", index);

if (index != -1)
deleteAndMoveEntry(symbol, index, sizeSymbol);
sizeSymbol--;
else if (index == -1)
fprintf(errorFile, "%sn", toDelete[i]);


for (i = 0; i < sizeSymbol; i++)
fprintf(out, "%sn", symbol[i]);

fclose(in);
fclose(out);
fclose(deleted);
fclose(errorFile);
return 0;


int binarySearch(char symbol[7], char toFind, int left, int right)
if (right >= left)
int mid = left + ((right - left) / 2);
if (strcmp(toFind, symbol[mid]) == 0)
printf("%dn", mid);
return mid;


if (strcmp(toFind, symbol[mid]) < 0)
binarySearch(symbol, toFind, left, mid - 1);

if (strcmp(toFind, symbol[mid]) > 0)
binarySearch(symbol, toFind, mid + 1, right);

return -1;


void deleteAndMoveEntry(char symbol[7], int index, int size)
int i;
for (i = index; i < size - 1; i++)
strcpy(symbol[i], symbol[i + 1]);


strcpy(symbol[i + 1], "");



stockin.txt, stockdel.txt

fopen()

perror()

stderr

2 Answers
2

The problem is most likely caused by missing return statements in the recursive calls. Change the lines

return

if (strcmp(toFind, symbol[mid]) < 0)
binarySearch(symbol, toFind, left, mid - 1);

if (strcmp(toFind, symbol[mid]) > 0)
binarySearch(symbol, toFind, mid + 1, right);


to

if (strcmp(toFind, symbol[mid]) < 0)
return binarySearch(symbol, toFind, left, mid - 1);

if (strcmp(toFind, symbol[mid]) > 0)
return binarySearch(symbol, toFind, mid + 1, right);


Without those return statements, execution falls to the bottom of the function, where the return value is -1, which explains the behavior you observed in main.

return

main

regarding: Please give me guidance on how to to post nice looking code here. One way to easily clean up the code formatting is to highlight/select all your code, then click the as that will (mostly) format your code. Then follow the axiom: only one statement per line and (at most) one variable declaration per statement.

In C, the range of valid index values is from 0 through (number of elements in array -1)

Regarding:

for (i = index; i < size - 1; i++) {
strcpy(symbol[i], symbol[i + 1]);


this expression: symbol[i+1], during the last loop, will be accessing beyond the end of the array.

symbol[i+1]

regarding:

strcpy(symbol[i + 1], "");


the index i will be pointing past the last entry in the array when the preceding for() loop has exited.

i

for()

So this: symbol[i+1] will be accessing 2 entries beyond the end of the array.

symbol[i+1]

Both of these problems result in undefined behavior

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