problem with pointers in my function

jzackt (16)
I'm pretty new to C and it seems like the only thing that is breaking my code is my lack of knowledge of pointers. I tried the beginner forum but no one can help. Here is my code: At the bottom is my grades.txt file. I would appreciate any kind of help...thanks

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



main()
{

FILE* fipoint;
double StudentGrades[20][3];
char StudentNames[20][9];
int x = 0,studentnum1;

double* grades;
char* names;
grades=StudentGrades;
names=StudentNames;


void minimum(char names_array[20][9], double grades_array[20][3]);
void maximum(char names_array[20][9], double grades_array[20][3]);
void average(int studentnum,double grades_array[20][3]);
/************************Task 1&2*************************************/
fipoint=fopen("grades.txt","r");

if(fipoint==NULL)
{
printf("Cannot open file!\n");
}
else
{
while(fscanf(fipoint,"%s",&StudentNames[x])>0)
{
fscanf(fipoint,"%lf", &StudentGrades[x][0]);
fscanf(fipoint,"%lf", &StudentGrades[x][1]);
fscanf(fipoint,"%lf", &StudentGrades[x][2]);

printf("%s %lf %lf %lf\n", StudentNames[x], StudentGrades[x][0],
StudentGrades[x][1], StudentGrades[x][2]);

x++;
}

fclose(fipoint);

}

/********************Task 3**************************************/


minimum((char)StudentNames,(double)StudentGrades);

maximum((char)StudentNames,(double)StudentGrades);
/********************Task 5**************************************/

printf("Which students average would you like to see?(1-20)\n\n");
scanf("%d",&studentnum1);
average(studentnum1,(double)StudentGrades);

system("pause");

}
/*****************************Minimum Function*********************************/
void minimum(char names_array[20][9], double grades_array[20][3])
{
int row=0,colmn=0,minrow=0;

int count=0;
double mini=0;


while(row<20){
if (grades_array[row][colmn]<=grades_array[row][colmn+1]){
mini==grades_array[row][colmn];
colmn++;

}

else {
mini==grades_array[row][colmn+1];
colmn++;
}

if(colmn==1){
row++;
colmn=0;
}

}

printf("Student %d had the lowest grade of %lf\n\n",minrow+1,mini);

}
/*****************************Maximum Function*********************************/
void maximum(char names_array[20][9], double grades_array[20][3])
{
int row2=0,colmn2=0,maxrow=0;

int count2=0;
double max=0;


while(row2<20){
if (grades_array[row2][colmn2]>=grades_array[row2][colmn2+1]){
max==grades_array[row2][colmn2];
colmn2++;

}

else {
max==grades_array[row2][colmn2+1];
colmn2++;
}

if(colmn2==1){
row2++;
colmn2=0;
}

}

printf("Student %d had the lowest grade of %lf\n\n",maxrow+1,max);

}
/**************************Average Function***********************************/
void average(int studentnum,double grades_array[20][3])
{
float aver, high, middle, low;


while(studentnum<1 || studentnum>20){
printf("This student does not exist");
}

if(grades_array[studentnum][0]>=grades_array[studentnum][1] && grades_array[studentnum][0]>=grades_array[studentnum][2]){/*****If first column is greatest**/
high=grades_array[studentnum][0]*.40;
if(grades_array[studentnum][1]>=grades_array[studentnum][2]){
middle=grades_array[studentnum][1]*.35;
low=grades_array[studentnum][2]*.25;
}
else{
middle=grades_array[studentnum][2]*.35;
low=grades_array[studentnum][1]*.25;
}
}

else if(grades_array[studentnum][1]>grades_array[studentnum][0] && grades_array[studentnum][1]>grades_array[studentnum][2]){/*****If second column is greatest**/
high=grades_array[studentnum][1]*.40;
if(grades_array[studentnum][0]>grades_array[studentnum][2]){
middle=grades_array[studentnum][0]*.35;
low=grades_array[studentnum][2]*.25;
}
else{
middle=grades_array[studentnum][2]*.35;
low=grades_array[studentnum][0]*.25;
}
}

else if(grades_array[studentnum][2]>grades_array[studentnum][0] && grades_array[studentnum][2]>grades_array[studentnum][1]){/*****If third column is greatest**/
high=grades_array[studentnum][2]*.40;
if(grades_array[studentnum][0]>grades_array[studentnum][1]){
middle=grades_array[studentnum][0]*.35;
low=grades_array[studentnum][1]*.25;
}
else{
middle=grades_array[studentnum][0]*.35;
low=grades_array[studentnum][1]*.25;
}
}

aver=high+middle+low;
printf("Student %d had and an average of %f",studentnum,aver);
}

Student1 77 68 86
Student2 50 60 35
Student3 45 87 90
Student4 60 87 90
Student5 34 56 4
Student6 1 2 3
Student7 67 75 81
Student8 23 45 90
Student9 1 50 100
Student10 34 65 86
Student11 38 98 78
Student12 67 54 97
Student13 99 98 87
Student14 17 71 7
Student15 64 86 87
Student16 56 78 65
Student17 23 45 76
Student18 69 96 87
Student19 45 78 88
Student20 80 81 90
translore (31)
I got the errors out and got it running but with many warnings. What exactly is this program supposed to do? The way you were casting was illegal so I took them out.
does this help any? 
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#include <stdio.h>
#include <math.h>
#include <stdlib.h>

int main()
{

FILE* fipoint;
double StudentGrades[20][3];
char StudentNames[20][9];
int x = 0,studentnum1;

double* grades;
char* names;
//grades=StudentGrades;
//names=StudentNames;


void minimum(char names_array[20][9], double grades_array[20][3]);
void maximum(char names_array[20][9], double grades_array[20][3]);
void average(int studentnum,double grades_array[20][3]);
/************************Task 1&2*************************************/
fipoint=fopen("grades.txt","r");

if(fipoint==NULL)
{
printf("Cannot open file!\n");
}
else
{
while(fscanf(fipoint,"%s",&StudentNames[x])>0)
{
fscanf(fipoint,"%lf", &StudentGrades[x][0]);
fscanf(fipoint,"%lf", &StudentGrades[x][1]);
fscanf(fipoint,"%lf", &StudentGrades[x][2]);

printf("%s %lf %lf %lf\n", StudentNames[x], StudentGrades[x][0],
StudentGrades[x][1], StudentGrades[x][2]);

x++;
}

fclose(fipoint);

}

/********************Task 3**************************************/


minimum(StudentNames, StudentGrades);

maximum(StudentNames,StudentGrades);
/********************Task 5**************************************/

printf("Which students average would you like to see?(1-20)\n\n");
scanf("%d",&studentnum1);
average(studentnum1,StudentGrades);

system("pause");

}
/*****************************Minimum Function*********************************/
void minimum(char names_array[20][9], double grades_array[20][3])
{
int row=0,colmn=0,minrow=0;

int count=0;
double mini=0;


while(row<20){
if (grades_array[row][colmn]<=grades_array[row][colmn+1]){
mini==grades_array[row][colmn];
colmn++;

}

else {
mini==grades_array[row][colmn+1];
colmn++;
}

if(colmn==1){
row++;
colmn=0;
}

}

printf("Student %d had the lowest grade of %lf\n\n",minrow+1,mini);

}
/*****************************Maximum Function*********************************/
void maximum(char names_array[20][9], double grades_array[20][3])
{
int row2=0,colmn2=0,maxrow=0;

int count2=0;
double max=0;


while(row2<20){
if (grades_array[row2][colmn2]>=grades_array[row2][colmn2+1]){
max==grades_array[row2][colmn2];
colmn2++;

}

else {
max==grades_array[row2][colmn2+1];
colmn2++;
}

if(colmn2==1){
row2++;
colmn2=0;
}

}

printf("Student %d had the lowest grade of %lf\n\n",maxrow+1,max);

}
/**************************Average Function***********************************/
void average(int studentnum,double grades_array[20][3])
{
float aver, high, middle, low;


while(studentnum<1 || studentnum>20){
printf("This student does not exist");
}

if(grades_array[studentnum][0]>=grades_array[studentnum][1] && grades_array[studentnum][0]>=grades_array[studentnum][2]){/*****If first column is greatest**/
high=grades_array[studentnum][0]*.40;
if(grades_array[studentnum][1]>=grades_array[studentnum][2]){
middle=grades_array[studentnum][1]*.35;
low=grades_array[studentnum][2]*.25;
}
else{
middle=grades_array[studentnum][2]*.35;
low=grades_array[studentnum][1]*.25;
}
}

else if(grades_array[studentnum][1]>grades_array[studentnum][0] && grades_array[studentnum][1]>grades_array[studentnum][2]){/*****If second column is greatest**/
high=grades_array[studentnum][1]*.40;
if(grades_array[studentnum][0]>grades_array[studentnum][2]){
middle=grades_array[studentnum][0]*.35;
low=grades_array[studentnum][2]*.25;
}
else{
middle=grades_array[studentnum][2]*.35;
low=grades_array[studentnum][0]*.25;
}
}

else if(grades_array[studentnum][2]>grades_array[studentnum][0] && grades_array[studentnum][2]>grades_array[studentnum][1]){/*****If third column is greatest**/
high=grades_array[studentnum][2]*.40;
if(grades_array[studentnum][0]>grades_array[studentnum][1]){
middle=grades_array[studentnum][0]*.35;
low=grades_array[studentnum][1]*.25;
}
else{
middle=grades_array[studentnum][0]*.35;
low=grades_array[studentnum][1]*.25;
}
}

aver=high+middle+low;
printf("Student %d had and an average of %f",studentnum,aver);
}
/*
Student1 77 68 86
Student2 50 60 35
Student3 45 87 90
Student4 60 87 90
Student5 34 56 4
Student6 1 2 3
Student7 67 75 81
Student8 23 45 90
Student9 1 50 100
Student10 34 65 86
Student11 38 98 78
Student12 67 54 97
Student13 99 98 87
Student14 17 71 7
Student15 64 86 87
Student16 56 78 65
Student17 23 45 76
Student18 69 96 87
Student19 45 78 88
Student20 80 81 90
*/
Last edited on
jzackt (16)
Thanks this helps alot. What all did you change though? The program takes a .txt file, splits it into 2 arrays, finds the min and makes grades, then takes the average...not too complicated.
jzackt (16)
What do you mean the way I was casting?
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