Mutiple function definition errors.

[Krabiki]

I am getting multiple function declaration errors when I try to execute the code.

I did a function declaration at the start, is the way I did it wrong ?

#include <stdio.h>
#include <stdlib.h>

int gradeint;
char grade;

/* function declaration */
int getMark();
void print(char grade);
char convert(int mark);

int main(int argc, char** argv) {
    getMark();
    convert(gradeint);
    print(grade);
    return (EXIT_SUCCESS);
}
 
int getMark(){
    printf("Enter your grade: ");
    scanf("%d", &gradeint);
    printf("What you have entered as your grade: %d\n", gradeint);
    return gradeint;
}

char convert(int mark){
    // converts int to char 
     grade = mark + '0';
     return grade;
}

void print(char grade){
    if(grade >= 80){
    printf("Your grade is an A\n");
    }
    else if (grade >= 70){
        printf("Your grade is a B\n");
    }
    else if (grade >= 60){
    printf("Your grade is a C\n");
        }
    else if (grade >= 50){
    printf("Your grade is a D\n");
        }
    else if (grade >= 40){
    printf("Your grade is an E\n");
        }       
    else{
    printf("Your grade is a F\n");
    }
}

[Hassan Ahmed]

program closed before you see any thing
no need to transform int to char (unless you need so for some reason (homework))

#include <stdio.h>
#include <stdlib.h>
 
int gradeint;

 
/* function declaration */
int getMark();
void print(int grade);

 
int main(int argc, char** argv) {
    
    print(getMark());
    system("pause");
    return (EXIT_SUCCESS);
}
  
int getMark(){
    printf("Enter your grade: ");
    scanf("%d", &gradeint);
    printf("What you have entered as your grade: %d\n", gradeint);
    return gradeint;
}
 

 
void print(int grade){
    if(grade >= 80){
    printf("Your grade is an A\n");
    }
    else if (grade >= 70){
        printf("Your grade is a B\n");
    }
    else if (grade >= 60){
    printf("Your grade is a C\n");
        }
    else if (grade >= 50){
    printf("Your grade is a D\n");
        }
    else if (grade >= 40){
    printf("Your grade is an E\n");
        }      
    else{
    printf("Your grade is a F\n");
    }
}

[Krabiki]

Yes, I need to transform it to char because the given printf() function accepts char parameters.

I did some debugging and some inspiration from your code, the issue seems to lie in the conversion.

The conversion of int to char doesn't work. Why ?

#include <stdio.h>
#include <stdlib.h>

int gradeint;
char grade;

/* function declaration */
int getMark();
void print(char grade);
char convert(int mark);

int main(int argc, char** argv) {
    //getMark();
    char retConvert;

    retConvert = convert(getMark());
    print(retConvert);
    return (EXIT_SUCCESS);
}
 
int getMark(){
    printf("Enter your grade: ");
    scanf(" %d", &gradeint);
    printf("What you have entered as your grade: %d\n", gradeint);
    return gradeint;
}

char convert(int mark){
    
     printf("mark is %d\n", mark); // prints correctly
     // converts int to char
     grade = mark + '0';
     printf( "grade is %c\n", grade); // prints wrongly 
     return grade;
}

void print(char grade){
    if(grade >= 80){
    printf("Your grade is an A\n");
    }
    else if (grade >= 70){
        printf("Your grade is a B\n");
    }
    else if (grade >= 60){
    printf("Your grade is a C\n");
        }
    else if (grade >= 50){
    printf("Your grade is a D\n");
        }
    else if (grade >= 40){
    printf("Your grade is an E\n");
        }       
    else{
    printf("Your grade is a F\n");
    }
}

[vart]

do not use the global variables.

All if/else logic from print should go into convert function

print will then be one liner

void print(char grade){
    printf("Your grade is an %c\n", grade);
}

[Krabiki]

vart , thanks for correcting my code logic and the errors .

On the other hand, why does a global variable not work ? A global variable is supposed to have the scope of the whole file right ?

[vart]

global variables work, but make maintaining of projects of any reasonable size - hell.

So you should from the beginning learn to avoid its usage when possible.

In your case - since you are passing everything as a parameter - you do not need globals at all