error if strcmp and getch show that undeclared

My error with line 20 if strcmp and line 75 getch show that undeclared,somebody
can help me.TQ!

Below is my error result:

Code:

#include <stdio.h>

main ()
{
    int credit_hour1,credit_hour2, totalcredithours;
    char fix_grade[3]="A";
    char grade1[3];
    char grade2[3];
    float calculation1, calculation2, totalcalculation,GPA;

    printf("Please enter your Grade for subject_1 :");
    scanf("%s",&grade1);
    printf("Please enter your credit hour for subject_1 :");
    scanf("%d",&credit_hour1);
    printf("Please enter your Grade for subject_2 :");
    scanf("%s",&grade2);
    printf("Please enter your credit hour for subject_2 :");
    scanf("%d",&credit_hour2);

    if(strcmp(grade1,"A" ) == 0)
    calculation1 = 4.00 * credit_hour1;
    if (strcmp(grade1, "A-")== 0)
    calculation1 = 3.67 * credit_hour1 ;
    if(strcmp(grade1,"B+" ) == 0)
    calculation1 = 3.33 * credit_hour1;
    if (strcmp(grade1, "B")== 0)
    calculation1 = 3.00 * credit_hour1;
    if(strcmp(grade1,"B-" )== 0)
    calculation1 = 2.67 * credit_hour1;
    if (strcmp(grade1, "C+")== 0)
    calculation1 = 2.33 * credit_hour1;
    if(strcmp(grade1,"C" ) == 0)
    calculation1 = 2.00 * credit_hour1;
    if (strcmp(grade1, "C-")== 0)
    calculation1 = 1.67 * credit_hour1;
    if(strcmp(grade1,"D+" ) == 0)
    calculation1 = 1.33 * credit_hour1;
    if (strcmp(grade1, "D")== 0)
    calculation1 = 1.00 * credit_hour1;
    if(strcmp(grade1,"F" ) == 0)
    calculation1 = 0.00 * credit_hour1;
    else
      if(strcmp(grade2,"A" ) == 0)
    calculation2 = 4.00 * credit_hour2;
    if (strcmp(grade2, "A-")== 0)
    calculation2 = 3.67 * credit_hour2 ;
    if(strcmp(grade2,"B+" ) == 0)
    calculation2 = 3.33 * credit_hour2;
    if (strcmp(grade2, "B")== 0)
    calculation2 = 3.00 * credit_hour2;
    if(strcmp(grade2,"B-" ) == 0)
    calculation2 = 2.67 * credit_hour2;
    if (strcmp(grade2, "C+")== 0)
    calculation2 = 2.33 * credit_hour2;
    if(strcmp(grade2,"C" ) == 0)
    calculation2 = 2.00 * credit_hour2;
    if (strcmp(grade2, "C-")== 0)
    calculation2 = 1.67 * credit_hour2;
    if(strcmp(grade2,"D+" ) == 0)
    calculation2 = 1.33 * credit_hour2;
    if (strcmp(grade2, "D")== 0)
    calculation2 = 1.00 * credit_hour2;
    if(strcmp(grade2,"F" ) == 0)
    calculation2 = 0.00 * credit_hour2;
    

totalcredithours = credit_hour1 + credit_hour2  ;  
totalcalculation = calculation1 + calculation2 ;
GPA = totalcalculation / totalcredithours ;

 printf("%.2f\n",totalcalculation);  
 printf("%d\n", totalcredithours); 
 printf("GPA %.2f\n", GPA);
    
getch();

}

strcmp is in string.h
getch is in conio.h, you should read the FAQ for better ways of stopping the window disappearing when the program ends.

This is C. Perhaps you should use a C compiler and put it in the C section.

ok. i try it 1st. tq!