Someone please help me to correct my error on the following code. Thank you. Her

Question

Someone please help me to correct my error on the following code. Thank you.

Here is the code.....
#include <iostream>


typedef struct NodeType {
char name; // the node's name
int weight; // the node's current weight
int pi; // the node's parent
} Node;

int graph[6][6] = {
{0,1,2,0,0,0},
{1,0,5,9,0,10},
{2,5,0,3,0,0},
{0,9,3,0,3,0},
{0,0,0,3,0,2},
{0,10,0,0,2,0}
};

Node node[6];
bool visited[6];

int getMinNode()
{
int index = -1;
for (int i=0; i<6; i++)
{
if (!visited[i])
{
index = i;
break;
}
}
for (int j=i+1; j<6; j++)
{
if (node[j].weight < node[index].weight) index = j;
}
return index;
}

void printResult(char *message) {
printf("%s ", message);
for (int i=0; i<6; i++) {
if (node[i].pi >= 0) {
int parent = node[i].pi;
printf("%c -- %c ", node[i].name, node[parent].name);
}
}
}

int main() { // Prim's algorithm

// Initialize the 6 nodes
for (int i=0; i<6; i++) {
node[i].name = 'A'+i;
node[i].pi = -1; // no parent
node[i].weight = 10000; // 10000 as infinity
visited[i] = false;
}
// Start from node 'A'
node[0].weight = 0;
int index = getMinNode();

// Prim's algorithm
while (index >= 0) {
visited[index] = true;
for (int j=0; j<6; j++) {
if (j==index) continue;
if (graph[j][index] == 0) continue;
int weight = node[index].weight + graph[j][index];
if (weight < node[j].weight) {
node[j].weight = weight;
node[j].pi = index;
}
}
index = getMinNode();
}

// Print out the result
printResult("Final Minimum Spanning Tree:");
}


Here is the error message I get on line 34. error C2065: 'i' : undeclared identifier Thanks in advance.

Explanation / Answer

well, i dont know what your code is doing, but to fix the error you have specified, change:

int getMinNode()
{
int index = -1;
for (int i=0; i<6; i++)
{
if (!visited[i])
{
index = i;
break;
}
}
for (int j=i+1; j<6; j++)
{
if (node[j].weight < node[index].weight) index = j;
}
return index;
}

to

basically, you were trying to access the variable i even though its scope had ended. just move the bracket down to include the for-loop. i dont know if this changes how the program is ran, but at least it does.

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