fprintf is not printing the data into the file - c

Question

I have written a code in C. Inside the for loop in main(), I have written the following. When I run the code, the fprintf statement is not writing the data into the datafile. I am adding edges to a graph. While adding, I am checking whether the pairs are already in the list using adjacent list. If the pairs are not in the list, I am adding the edges, using the function call addEdge():
int main()
{
FILE *ed = NULL;
ed = fopen("c2.txt","w");
FILE *ls = NULL;
ls = fopen("e2.txt", "w");
FILE *lk = NULL;
lk = fopen("link2.txt","w");
if(ls == NULL){
printf("Error in opening file ls!\n");}
if(ed == NULL){
printf("Error in opening file ed!\n");}
if(lk == NULL){
printf("Error in opening file lk!\n");}
else
{
int src,dest;
int src1,dest1;
int i,k,v;
int NV = 500 #No. of nodes
int m = 10000 #No. of edges
int nblinks = 0; # edge counter:
double x[NV],x1[NV];
double x2[NV];
unifRand(x,x1,x2); // function call for infection rate:Pass only name of array:
int ss[NV];
data1(ss); // function call for generated data:
double sum,sum1 = 0.0;
double R = 0.00268; //Learning rate: // (i) 0.01 // ii. 0.001 // (iii) 0.00251 (iv)0.00268
double L[NV][NV-1];
double L1[NV][NV-1];
double L_old[NV][NV-1];
double L2[NV][NV-1];
double t = 0, dt = 0.1;
double C;
struct Graph* graph = createGraph(NV); // Function call for graph:
int d;
int nblinks = 0; // Edge counter:
L_old[0][1] = 0.01; // choice of initial coupling/guess : 0.02
for(i=0; i<NV-1; i++)
{
x2[i] = 0.02;
}
fprintf(ed,"True\t\tMeasured\t x[i]\t\t x1[i]\t\t x2[i]\t\tsum\t\t Error\t\ttime\tnode\n");
fprintf(ed,"------------------------------------------------------------------------------------------------------------\n");
fprintf(lk," Pair of Nodes:\n");
fprintf(lk,"---------------------------------------------------------------------\n");
for( i = 0, k = 1; i < NV-1; i++)
{
struct AdjListNode* temp = graph->array[i].head;
printGraph(graph, &sum, temp);
# if the adjacent node is not zero:
while(temp != NULL && temp->next != NULL)
{
fprintf(ls,"%d %d\n", i, temp->dest);
temp = temp->next;
while(nblinks < m)
{
#Random numbers for source and destination nodes:
int src1 = random()%NV;
int dest1 = random()%NV;
if(src1 < dest1)
{
src = src1;
dest = dest1;
}
else
{
src = dest1;
dest = src1;
}
int pairs[2] = {src, dest};
//If pairs are not in the list, add the edges then:
if(src != dest && pairs[2] != (i, temp->dest))
{
printf("%d\t%d\n",src,dest);
fprintf(lk,"(%d,%d)\t(%d,%d)\n", pairs[0],pairs[1],i, temp->dest);
addEdge(graph, src, dest);
nblinks++; // counter:
} // End if
} //End while1 :
} // End while 2:
# I have written my calculation here :
fprintf(ed,"%0.6lf\t%0.6lf\t%0.6lf\t%0.6lf\t%0.5lf\t\t%0.6lf\t%0.6lf\t%0.1lf\t%d\t%0.6lf\n", L[i][k],L1[0][1],x[i],x1[i],
x2[i],sum1,C, t,ss[k],L2[i][k]);
} // End for
} // End else
fclose(ed);
fclose(ls);
fclose(lk);
ed = NULL;
ls = NULL;
lk = NULL;
return 0;
}

Answer 1

This code is quite strange and some parts of it should not be compiled by c compiler.
E.g.:
int NV = 500 #No. of nodes
int m = 10000 #No. of edges
int nblinks = 0; # edge counter:
where #No. of nodes is like comment and int NV = 500 has no ; in the end - so is not completed line of code.
Style is also not perfect, e.g.:
if(ls == NULL){
printf("Error in opening file ls!\n");}
if(ed == NULL){
printf("Error in opening file ed!\n");}
if(lk == NULL){
printf("Error in opening file lk!\n");}
else
{
should be
if(ls == NULL)
{
printf("Error in opening file ls!\n");
return 1;
}
if(ed == NULL)
{
printf("Error in opening file ed!\n");
return 1;
}
if(lk == NULL)
{
printf("Error in opening file lk!\n");
return 1;
}
// no else needed after 3 way to the exit (return)
or better
if(!lk || !ed || !ls)
{
printf("Error in opening on of the files\n");
return 1;
}
In general, if all files are opened in the required mode (and after all writing are closed) no problem should be with fprintf except incorrect format string or wrong data for output.
UPDATE:
Just to check output, you can use stdout as the first argument of fprintf to see result at the screen (console), or make lk = stdout; instead of lk = fopen("link2.txt", "w");.
Then if you see data at the screen look what is wrong with the file.