a bit stuck- subscripted value is neither array nor pointer...

[andyIOM]

okay, i have tried,googled and read but havn't managed to figure out where the error is.

bascically,my file reads an in put file which looks like this:

Is 2 1 50
R1 2 9 500
R2 1 0 100
R3 2 2 900
R4 2 1 100

then it finds the max node (i.e. 9 in this case) creates a matrix by max_node,

then outputs the new matrix with the values from the input file... supposedly.

but i can't seem to get it to work at all.

the error is this:

c.c:40: error: subscripted value is neither array nor pointer.

and the file is this

#include <stdlib.h>
#include <stdio.h>
 
int main (void)
 
{    
  char R,I,line [256];
 
    int i,j, node1, node2, max_node=0;
    double value, **matrix, *mtx, *temp;
 
FILE *program1;    
 
  program1=fopen("text.txt", "r");
 
  if (program1==NULL)
    {
      printf("Unable to read file\n");
      return (0);
    }
 
while (fscanf(program1,"%s %d %d %lf", line, &node1, &node2, &value)!=EOF)
    {    if (max_node<node1)    
    {
        max_node=node1;
    } 
        else if (max_node<node2)
    {
        max_node=node2;
    }    
    }         
    printf("max_node %d\n", max_node);        // All working, Max_node correct
 
temp=(double *)malloc(max_node*max_node*sizeof(double));
matrix=(double **)malloc(max_node*sizeof(double *));
 
rewind(program1);
//printf("%d",node1);
while (fscanf(program1,"%s %d %d %lf", line, &node1, &node2, &value)!=EOF)
{    
     if (line[0]=='R')
      { // Resistor
      printf("%d",node1);
    temp[node1][node1] += 1.0/value; // Diagonal  <<---LINE 40 - ERROR HERE
    temp[node2][node2] += 1.0/value; // Diagonal
    temp [node1][node2] -= 1.0/value; // Off-Diagonal
    temp [node2][node1] -= 1.0/value; // Off-Diagonal
     }
    else if (line[0]== 'I')
    {    // Current Source
 
      mtx[node1]+=value;
      mtx[node2]-=value;
    }
 
    for (i=0;i<max_node;i++)
    {
        for(j=0;j<max_node;j++)
        {
        printf("%lf    ", temp[i][j]);
        }
        printf("\t%lf\n", matrix[i]);
        }
    }*/
 
}
 

i hope it's clear to where the error is.

thanks, andy

[RRick]

Your temp array is of the right size, but the wrong dimension. Temp's dimension is one, not two. To make a 2 dimensional array, you need 2 steps and a loop.

 
 #include <stdlib.h>
 
 int main (void)
 {   
    int rows=4, cols=5;
    double ** temp;
 
    temp = (double**) malloc( sizeof( double *) * rows);
    for ( int ind=0; ind<rows; ind++)
    {
        temp[ ind] = (double*) malloc( sizeof( double) * cols);
    }
}