Iterating through a two dimensional array column wise in c - c

Question

Please can someone explain to me how to iterate through a two dimensional array column wise i.e keeping the row constant until we reach the end of the column?
Thanks.
I'm writing a program to calculate scores of some subjects in a class of students. It calculates the total marks obtained by each student and also the highest mark in each subject.
The tricky part i'm having difficulty is calculating the lowest mark in each subject. This will require to iterate downwards each column and change the row only after getting the highest score in that column(subject)
The code (also - http://pastebin.com/FmP4yX59 ):
#include <stdio.h>
#include <stdlib.h>
#define MAX_ST 3
#define MAX_SU 3
int main() {
int student[MAX_ST][MAX_SU];
int total_mark[MAX_ST];
printf("\n_________________PRESS TAB KEY TO SHIFT A COLUMN_________________\n");
printf("\nRoll_NO subject1 subject2 subject3\n");
printf("________________________________________________________________\n");
for(int i = 0; i < MAX_ST; i++) {
printf("%d\t|\t",i+1);
for(int j = 0; j < MAX_SU; j++){
scanf("%d",&student[i][j]);
}
}
//total marks obtained by each student
printf("\nTOTAL MARKS\n");
for(int i = 0; i < MAX_ST; i++) {
total_mark[i] = 0;
for(int j = 0; j < MAX_SU; j++) {
total_mark[i] += student[i][j];
}
printf("Student %d = %d\n",i+1, total_mark[i]);
}
//highest total mark
int overRoll = 0;
int high_S = 0;
for(int i = 0; i < MAX_ST; i++) {
if(high_S <= total_mark[i]) {
high_S = total_mark[i];
overRoll = i;
}
}
printf("Highest total marks is %d for Student %d\n", high_S,overRoll + 1);
//highest mark in each subject
//where the problem lies
int highest_mark[MAX_SU];
int highest_sudent[MAX_SU];
for(int i = 0; i < MAX_SU;i++){
for(;j = t;) {
Highest_mark[i] = 0;
if(student[i][j] > highest_mark[i]) {
highest_mark[j] = student[][j];
highest_student[i] = i;
}
}
printf("the highest");
}
}

Answer 1

Typically you'd do something like this:
typedef void action_t (int*);
void traverse_matrix ( size_t col,
size_t row,
int matrix[col][row],
action_t* action )
{
for(size_t x=0; x<col; x++)
{
for(size_t y=0; y<row; y++)
{
action(&matrix[x][y]);
}
}
}

Answer 2

#define rows 5
#define columns 4
int matrix[rows][columns];
int r, c;
for (c = 0; c < columns; c++)
{
for (r = 0; r < rows; r++)
{
matrix[r][c]; \\ the data
}
}

Answer 3

thanks guys for helping me figure it out
int highest_mark[MAX_SU];
int highest_student[MAX_SU];
int curr_sub;
for(int i = 0; i < MAX_SU; i++)
{
highest_mark[i] = 0;
for(int j = 0; j < MAX_ST; j++)
{
if(student[j][i] > highest_mark[i])
{
highest_mark[i] = student[j][i];
highest_student[i] = j+1;
curr_sub = i+1;
}
}
printf("the highest score subject %d is %d by student %d\n", curr_sub, highest_mark[i],highest_student[i]);
}