Question

I am rather new to C and am probably doing something stupid but I can’t find out why my string array isn’t keeping the previous values while the grade is keeping all the values entered:

for(int i=0; i <noOfStudents; i++)
{
    do{
        printf("Please enter Student Full Name.");
        //read string till enter
        scanf(" %[^\n]", &studentFullName);
        if(studentFullName == "")
        {
            printf("Invalid Student Name!\n\n");
            getchar();
        }
        else
        {
            names[i] = studentFullName;
            validStudentName = 1;
        }
    }while(validStudentName != 1);

    do{
        printf("Please enter Student Grade.");
        scanf_s(" %d", &grade);
        if(grade < -1 && grade >100)
        {
            printf("Invalid Student Grade!\n\n");
            getchar();
        }
        else
        {
            grades[i] = grade;
            validGrade = 1;
        }
    }while(validGrade != 1);

    printf("\n");
}

Answer 1

grade is an integer. When you do:

int a;
int b = 3;
a = b;
b = 4;

then a continues to be 3, because integers are copied.

studentFullName is, however, a pointer. Just like integers, pointers are copied. However, the data the pointer points to is not. So, basically, you’ve got your entire names[] array as a bunch of pointers, all pointing to the exact same data.

There are several functions that will copy the pointed-to data for you, the one you’re looking for is probably strdup. Note that you must free all the pointers you get back from strdup.