Question about C syntax

I have a friend who was working on a c example from a book and he did a code like

#include<stdio.h>
#include<math.h>
#pragma warning(disable:4996)

int main()
{
    float numGrade;

    printf("\n\nPlease enter your numerical grade: ");
    scanf("%f", &numGrade);

    if (numGrade >= 90)
        printf("\nYou got an A.\n\n");
    else if (90 > numGrade >= 80)
        printf("\nYou got a B.\n\n");
    else if (80 > numGrade >= 70)
        printf("\nYou got a C.\n\n");
    else if (70 > numGrade >= 60)
        printf("\nYou got a D.\n\n");
    else if (60 > numGrade)
        printf("\nYou got an F.\n\n");
    else
        printf("\nThis is an invalid grade!\n");
}

Is there any problem with doing it like that or should he do it like :

int main()
{
    float numGrade;

    printf("\n\nPlease enter your numerical grade: ");
    scanf("%f", &numGrade);

    if (numGrade >= 90)
        printf("\nYou got an A.\n\n");
    else if (90 > numGrade && numGrade >= 80)
        printf("\nYou got a B.\n\n");
    else if (80 > numGrade && numGrade >= 70)
        printf("\nYou got a C.\n\n");
    else if (70 > numGrade && numGrade >= 60)
        printf("\nYou got a D.\n\n");
    else if (60 >开发者_Python百科 numGrade)
        printf("\nYou got an F.\n\n");
    else
        printf("\nThis is an invalid grade!\n");
}

That first example won't work at all.

The first comparison in each test will return either 0 or 1. So it will always fail the second.

EDIT:

However, the program will probably still "work" the way it is desired, simply because the second comparison in each test is not needed.