My Binary search function will not find the actual name it is looking for

Question

I am working on this code where you'll need to compare last names and first names and swap them in alphabetical order. I got that right but when I need to find the name and print that using my binary search function searching for the last name it will not print out the correct data or record. It will print a different name record. I am using pointers and calling functions. Please help. (int main()) was already provided

struct _student
{
    char firstname[16];
    char lastname[16];
    char address[32];
    char city[24];
    char county[24];
    char state[3];
    char zip[9];
    char phone[16];
    char email[36];
};
typedef struct _student Student;

void swap(Student* s1, Student* s2)
{
    Student Swap;
    Swap = *s1;
    *s1 = *s2;
    *s2 = Swap;
}

int nameCmp(Student* s1, Student* s2)
{
    int result1 = strcmp(s1->lastname, s2->lastname);
    int result2 = strcmp(s1->firstname, s2->firstname);

    if (result1 < 0)
    {
        return -1;
    }
    else if (result1 == 0)
    {
        if (result2 < 0)
        {
            return -1;
        }
        else if (result2 == 0)
        {
            return 0;
        }

        return 0;
    }
    else
    {
        return 1;
    }
}

void exchangeSort(Student s[], int count, int (*compare)(Student*, Student*))
{
    
    for (int i = 0; i < count - 1; i++)
    {
        for (int j = i + 1; j < count; j++)
        {
            if (compare(&s[i], &s[j]) > 0)
            {
                swap(&s[i], &s[j]);
            }
        }
    }
}

int bSearch(Student data[], int count, char name[], int (*compare)(Student*, Student*))
{
    int low = 0, high = count - 1;
    while (low <= high)
    {
        int mid = (high + low) / 2;
        int cmp = compare(name, &data[mid]);
        if (cmp == 0)
            return mid;
        if (cmp > 0)
        high = mid - 1; 
        else
        low = mid + 1;  
    }

}

int readRowFromFile(FILE* f, Student* s)
{
    memset(s, 0, sizeof(Student));
    return fscanf(f, " %[^,], %[^,], %[^,], %[^,], %[^,], %[^,], %[^,], %[^,], %s\n",
        s->firstname, s->lastname, s->address, s->city, s->county, s->state, s->zip, s->phone, s->email);
}

// Main routine
int main()
{
    // Variable to hold the print format string
    char* fmt = "%-12s%-16s%-32s%-20s%-3s%-6s%-24s\n";

    // Declare an array variable to hold all the records
    Student rData[1000];

    // Open the file for reading, MAKE SURE THE FILE NAME MATCHES WHAT YOU HAVE
    FILE* f = fopen("Samplerecords.csv", "rt");
    if (!f)
    {
        printf("Unable to open file. \n");
        keypress();
        return 0;
    }

    // Variable to hold the number of records actually read
    int count = 0;

    // Skip the header row
    int rc = readRowFromFile(f, &rData[0]);

    // Read the rest of the file
    while (!feof(f) && count < 1000)
    {
        rc = readRowFromFile(f, &rData[count]);
        if (rc > 0)
            count++;
    }

    // Close the file
    fclose(f);

    // Print the first 10 records before sorting
    printf("Before sorting:\n");
    for (int i = 0; i < 10; i++)
    {
        printf(fmt, rData[i].firstname, rData[i].lastname,
            rData[i].address, rData[i].city, rData[i].state, rData[i].zip, rData[i].email);
    }

    // Sort the records by name
    exchangeSort(rData, count, nameCmp);

    // Print the first 10 records after sorting
    printf("\n\nAfter name sort:\n");
    for (int i = 0; i < 10; i++)
    {
        printf(fmt, rData[i].firstname, rData[i].lastname,
            rData[i].address, rData[i].city, rData[i].state, rData[i].zip, rData[i].email);
    }

    // Find the index of the record of "Bernardo Figueroa" (search last name only)
    int index = bSearch(rData, count, "Figeroa", nameCmp);
    if (index >= 0)
    {
        printf("\nFound:\n");
        printf(fmt, rData[index].firstname, rData[index].lastname,
            rData[index].address, rData[index].city, rData[index].state, rData[index].zip, rData[index].email);
    }
    else
    {
        printf("\nRecord not found\n");
    }

    keypress();
    return 0;
}

Output

Answer 1

The first thing you need to learn is to set a high warning level for your compiler and then fix all warnings before you run the program.

For gcc you can use the flags -Wall -Wextra and maybe also -Werror. When I compile your code with the flags -Wall -Wextra, I get:

main.cpp: In function 'bSearch':
main.cpp:132:27: warning: passing argument 1 of 'compare' from incompatible pointer type [-Wincompatible-pointer-types]
  132 |         int cmp = compare(name, &data[mid]);
      |                           ^~~~
      |                           |
      |                           char *
main.cpp:132:27: note: expected 'Student *' {aka 'struct _student *'} but argument is of type 'char *'
main.cpp:141:1: warning: control reaches end of non-void function [-Wreturn-type]
  141 | }
      | ^

These two warnings tells all about bugs in your code, i.e.

1. Your compare function can't be used for comparing a Student with a string

2. The bSearch function is missing a return when no match is found

Further, notice that the search is supposed to look for last name only but your nameCmp looks at both first and last name. So you need another compare function for the search.