Split up program with 2 dimensional arrays into Functions (C) - c

Question

I've written a program in C which allows me to move around in a "room" which is a 2 dimensional array. It works fine, but now I am running into issues when trying to split it up into functions. I might approach it completely wrong as I've only worked in Visual Basic, where stuff like this is much easier.
The void functions with printf also work perfectly fine.
Here's my code:
#include <stdio.h>
void instruction(void) {
printf("Move: W=up, D=right, S=down, A=left an apply with RETURN.\n");
}
void wall(void) {
printf("##### You are in front of a wall. Please move somewhere else! #####\n");
}
int runter(roomxy, y, x, index) {
roomxy[y][x] = 0;
y = y + 1;
if (y>3 || y<0) {
y = y - 1;
wall();
index--;
return (index);
}
return (roomxy[y][x]);
}
void main() {
char c[2];
int steps;
int i;
int j;
int k;
int room[4][4] = { 0 };
int ypos = 0;
int xpos = 0;
room[ypos][xpos] = 1;
for(j=0; j<4; j++) {
for(k=0; k<4; k++) {
printf("%d ", room[j][k]);
}
printf("\n");
}
printf("How many steps do you want to make? (Number from 1 to 50.)\n");
scanf("%d", &steps);
if (steps>0 && steps<51) {
for (i=1; i<=steps; i++) {
instruction();
scanf("%s", c);
if (c[0] == 'S' || c[0] == 's') {
room = runter(room, ypos, xpos, i);
/*room[ypos][xpos] = 0;
ypos = ypos + 1;
if (ypos>3 || ypos<0) {
ypos = ypos - 1;
wall();
i--;
}*/
}
else if (c[0] == 'W' || c[0] == 'w') {
room[ypos][xpos] = 0;
ypos = ypos - 1;
if (ypos>3 || ypos<0) {
ypos = ypos + 1;
wall();
ypos = ypos + 1;
wall();
i--;
}
}
else if (c[0] == 'D' || c[0] == 'd') {
room[ypos][xpos] = 0;
xpos = xpos + 1;
if (xpos>3 || xpos<0) {
xpos = xpos - 1;
wall();
i--;
}
}
else if (c[0] == 'A' || c[0] == 'a') {
room[ypos][xpos] = 0;
xpos = xpos - 1;
if (xpos>3 || xpos<0) {
xpos = xpos + 1;
wall();
i--;
}
}
else {printf("##### ERROR: Only type in W, D, S or A! #####\n"); i--;}
room[ypos][xpos] = 1;
printf("Ihre Position:\n");
for(j=0; j<4; j++) {
for(k=0; k<4; k++) {
printf("%d ", room[j][k]);
}
printf("\n");
}
}
}
else {printf("##### Please enter number from 1 to 50! #####\n");}
}
The error I am getting is "subscripted value is neither array nor pointer nor vector".
I don't know how to move on as I am completely stuck at trying to figure out how functions with arrays work in C.
I've also read about the typedef argument, but I also don't really know how to work with it.
Obviously I am a bloody noob at programming in general.
Thank you guys in advance!

Answer 1

Your source code is muddled, so there are a number of things to fix.
First, change void main() to int main(void). That is just required by the C standard; main must be either int main(void) or int main(int argc, char *argv[]) in normal situations.
Next, you must declare parameter types when you declare a function. int runter(roomxy, y, x, index) is wrong because it fails to say what types the parameters are. Likely, you want either int runter(int roomxy[][4], int y, int x, int index) or int runter(int *roomxy, int y, int x, int index). The former passes the entire array (by way of a pointer to its first subarray) to runter. The latter passes a pointer to a specific element. The first should be used if runter needs to work with multiple elements of the array. The second should be used if runter needs to work with only a specific element. However, using the second form requires additional changes in your program, and it requires use of pointers that you may not have learned about yet, so I am going to omit discussion of that.
Then, it is not clear what you want runter to return. In one place inside the function, you have return (index);. In another, you have return (roomxy[[y][x]);. It is not clear to me whether the index and roomxy[y][x] are two possible values of one kind of thing you want to return or whether they are different kinds of things. If they are the same kind of thing, okay. But if they represent different things, it generally does not make sense for a function to return one or the other.
In any case, return statements do not need parentheses. return index; and return roomxy[y][x] are fine.
Where you call runter, you have room = runter(room, ypos, xpos, i);. This does not make sense because room is an array but runter returns an int. You cannot assign an int to an array. Perhaps you meant room[ypos][xpos] = runter(room, ypos, xpos, 1);. (If so, then it does appear you want runter to work with a single element, so the pointer-to-an-element solution would be better. But you can get the program working and then worry about that.)

Answer 2

I have modified your source. in runter() you are returning int and have catch with room which is pointer(2 dimensional). it's impossible.
Add on to this you should have declare datatype in int runter(roomxy, y, x, index). I have corrected it.
#include <stdio.h>
void instruction(void) {
printf("Move: W=up, D=right, S=down, A=left an apply with RETURN.\n");
}
void wall(void) {
printf("##### You are in front of a wall. Please move somewhere else! #####\n");
}
void runter(int roomxy[][4], int y, int x, int index) {
roomxy[y][x] = 0;
y = y + 1;
if (y>3 || y<0) {
y = y - 1;
wall();
index--;
// return (index);
}
// return (roomxy[y][x]);
}
int main() {
char c[2];
int steps;
int i;
int j;
int k;
int room[4][4] = { 0 };
int ypos = 0;
int xpos = 0;
room[ypos][xpos] = 1;
for(j=0; j<4; j++) {
for(k=0; k<4; k++) {
printf("%d ", room[j][k]);
}
printf("\n");
}
printf("How many steps do you want to make? (Number from 1 to 50.)\n");
scanf("%d", &steps);
if (steps>0 && steps<51) {
for (i=1; i<=steps; i++) {
instruction();
scanf("%s", c);
if (c[0] == 'S' || c[0] == 's') {
/* room[ypos][xpos] = */runter(room, ypos, xpos, i);
room[ypos][xpos] = 0;
ypos = ypos + 1;
if (ypos>3 || ypos<0) {
ypos = ypos - 1;
wall();
i--;
}
}
else if (c[0] == 'W' || c[0] == 'w') {
room[ypos][xpos] = 0;
ypos = ypos - 1;
if (ypos>3 || ypos<0) {
ypos = ypos + 1;
wall();
/* ypos = ypos + 1;
wall();*/
i--;
}
}
else if (c[0] == 'D' || c[0] == 'd') {
room[ypos][xpos] = 0;
xpos = xpos + 1;
if (xpos>3 || xpos<0) {
xpos = xpos - 1;
wall();
i--;
}
}
else if (c[0] == 'A' || c[0] == 'a') {
room[ypos][xpos] = 0;
xpos = xpos - 1;
if (xpos>3 || xpos<0) {
xpos = xpos + 1;
wall();
i--;
}
}
else {printf("##### ERROR: Only type in W, D, S or A! #####\n"); i--;}
room[ypos][xpos] = 1;
printf("Ihre Position:\n");
for(j=0; j<4; j++) {
for(k=0; k<4; k++) {
printf("%d ", room[j][k]);
}
printf("\n");
}
}
}
else {printf("##### Please enter number from 1 to 50! #####\n");}
return 0;
}