Compiler Error says main must return int. Why? I just need tomake this code work. Thats all.

COMPILER ::

gmichel@ubuntu:~/Desktop/CS302REDO/Project6$ g++ -Wall-std=c++11 pro6.cpp -o project
pro6.cpp:148:11: error: ‘::main’ must return ‘int’
void main()
^
pro6.cpp: In function ‘int main()’:
pro6.cpp:152:16: warning: unused variable ‘count’[-Wunused-variable]
int inputa[20],count=0;
^
pro6.cpp: In function ‘node* search(node**, int)’:
pro6.cpp:99:1: warning: control reaches end of non-void function[-Wreturn-type]
}
^
gmichel@ubuntu:~/Desktop/CS302REDO/Project6$

CODE THAT I AM USING:

#include
#include
#include
struct bin_tree {
int data;
struct bin_tree * right, * left;
};
typedef struct bin_tree node;
FILE *fptr;
void insert(node ** tree, int val)
{
node *temp = NULL;
if(!(*tree))
{
temp = (node *)malloc(sizeof(node));
temp->left = temp->right = NULL;
temp->data = val;
*tree = temp;
return;
}

if(val < (*tree)->data)
{
insert(&(*tree)->left, val);
}
else if(val > (*tree)->data)
{
insert(&(*tree)->right, val);
}

}

void print_preorder(node * tree)
{
if (tree)
{
//printf("%d",tree->data);
fprintf(fptr,"%d",tree->data);
print_preorder(tree->left);
print_preorder(tree->right);
}

}

void print_inorder(node * tree)
{
if (tree)
{
print_inorder(tree->left);
//printf("%d",tree->data);
fprintf(fptr,"%d",tree->data);
print_inorder(tree->right);
}
}

void print_postorder(node * tree)
{
if (tree)
{
print_postorder(tree->left);
print_postorder(tree->right);
//printf("%d",tree->data);
fprintf(fptr,"%d",tree->data);
}
}

void deltree(node * tree)
{
/*if (tree)
{
deltree(tree->left);
deltree(tree->right);

free(tree);
tree=NULL;
}*/
tree=NULL;
}

node* search(node ** tree, int val)
{
if(!(*tree))
{
return NULL;
}

if(val < (*tree)->data)
{
search(&((*tree)->left), val);
}
else if(val > (*tree)->data)
{
search(&((*tree)->right), val);
}
else if(val == (*tree)->data)
{
return *tree;
}
}
/*------------------------------------------*/
void calhd(node *ptr){

int depth1 = 0, depth2 = 0;
node *root1=ptr;
ptr = root1;
while (ptr->left != NULL || ptr->right != NULL)
{
depth1++;
if (ptr->left == NULL)
ptr = ptr->right;
else
ptr = ptr->left;
}
ptr = root1;
while (ptr->left != NULL || ptr->right != NULL)
{
depth2++;
if (ptr->right == NULL)
ptr = ptr->left;
else
ptr = ptr->right;
}
/*
*DEPTH IS CONSIDERED FROM LEVEL-0 ALSO HEIGHT IS CONSIDERED ASNUMBER OF EDGES
*/
if (depth1 > depth2){

fprintf(fptr,"height of the tree is %d",depth1);
fprintf(fptr,"Level of the binary tree is %d (Assume that root islevel 0)",depth1-1);
}
else
fprintf(fptr,"height of the tree is %d",depth2);
fprintf(fptr,"Level of the binary tree is %d (Assume that root islevel 0)",depth2-1);

}
/*------------------------------------------*/
void isempty(node *tree)
{
if(tree==NULL)
{
fprintf(fptr,"%s","tree is empty");
return;
}
fprintf(fptr,"%s","Tree is not empty");
}
/*---------------------------------------------------------------------------------------------------*/
void main()
{
node *root;
node *tmp;
int inputa[20],count=0;
int j=0,k;
int choi;
root = NULL;
fptr=fopen("outlast.txt","w");
fprintf(fptr,"%s", "OUTPUT");
fclose(fptr);
fptr=fopen("outlast.txt","a+");
/* Inserting nodes into tree */
/******************************************/
FILE* file = fopen ("in.txt", "r");
int i = 0;

fscanf (file, "%d", &i);
while (!feof (file))
{
inputa[j++]=i;
fscanf (file, "%d", &i);
}
fclose (file);
/*******************************************/
for(k=0;kinsert(&root, inputa[k]);
}
fprintf(fptr,"No of nodes in the binary tree is %d",j);
/* Printing nodes of tree */
//printf("Pre Order Display");
fprintf(fptr,"%s","Pre Order Display");
print_preorder(root);

//printf("In Order Display");
fprintf(fptr,"%s","In Order Display");
print_inorder(root);

//printf("Post Order Display");
fprintf(fptr,"%s","Post Order Display");
print_postorder(root);

/* Search node into tree */
int se;
printf("Enetr item for search: ");
scanf("%d",&se);
tmp = search(&root, se);
if (tmp)
{
fprintf(fptr,"Searched node=%d", tmp->data);
}
else
{
fprintf(fptr,"%s","Data Not found in tree.");
}
do{
printf("Do you want to check if BST is empty of not ? (1 for Yes/2for No): ");
scanf("%d",&choi);
switch(choi)
{
case 1:
isempty(root);
choi=2;
break;
case 2:
break;
default:
printf("Enter valid input.");
break;
}
}while(choi!=2);

calhd(root);
/* Deleting all nodes of tree */
do{
printf("Do you want to Delete BST ? (1 for Yes/2 for No): ");
scanf("%d",&choi);
switch(choi)
{
case 1:
root=NULL;
choi=2;
isempty(root);
break;
case 2:
break;
default:
printf("Enter valid input.");
break;
}
}while(choi!=2);
fclose(fptr);
}

Answer rating: 100% (QA)

The compiler error says main must return int because main is a function and it is expected to return ... View the full answer