UNIX for Dummies Questions & Answers

Here's a program and its pretty simple .It requires file handling and some calculations but on running it I am not getting the required result.It seems that the code outside the file read's outer while loop is not executing e.g the print statement is not being printed.Plz Help!

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>

int main(int argc,char *args[])
{
FILE *fp;
char ch;
int load=0,value=0,weight=0;
int i=0,count=0,p,k=1,j,*cost,line=1,u;
if(argc!=2){
printf("\nInsufficient no. of arguments");
exit(0);
}
fp=fopen(args[1],"r");
if(fp==NULL){
printf("\nFile could not be opened");
exit(0);
}
while((ch=fgetc(fp))!='\n'){
if(isdigit(ch)){
p=ch-'0';
load=load*10+p;
}
}
printf("\nload= %d \n",load);
i=0;
while((ch=fgetc(fp)!=EOF)){
value=0;
weight=0;
k=0;
u=0;
while(ch!='\n'){
// printf("\nline=%d,weight=%d,value=%d",line,weight,value);

if((isalpha(ch)||isdigit(ch))&&k==0){
while(ch!=' '){
ch=fgetc(fp);
}
k++;
}
if(weight==0){
while(ch!=' '){
p=ch-'0';
weight=weight*10+p;
ch=fgetc(fp);
}
}
// printf("\nweight=%d",weight);
if(value==0){
while(ch!='\n'){
p=ch-'0';
value=value*10+p;
ch=fgetc(fp);
}
}
// printf("\nValue=%d",value);
if(ch==' '){
while(ch==' '){
ch=fgetc(fp);
}
}
}

u=value/weight;
printf("line=%d weight=%d,value=%d,cost=%d\n",line,weight,value,u);
line++;
}
// count=i-1;
fclose(fp);
return 0;
}

The text file that I am using is strictly of the following format:
1250
LJS93K 1300 10500
J38ZZ9 700 4750
HJ394L 200 3250
01IE82 75 10250

there is a line-break after each line and the first line(1250) is the "load" value,the first column of every is to be avoided the 2nd column is weight and the 3rd column is value.
One more thing I am using ubuntu distro which uses bash shell!

Code tags for code please, they make the unreadable readable. [ code ] stuff [ /code ] without the extra spaces.

You get 'floating point error' when you divide by zero, check to see if things are getting parsed the way you expect.

You do not need to use fgetc to read in text data! Try scanf. Or better yet, sscanf. Read in data one line at a time then feed it through scanf to get what you want in one go.

Code:

char buf[512], garbage[512];
if(fgets(buf, 512, fp)==NULL0
{
  fprintf(stderr, "Can't read first line\n");
  return(1);
}

if(sscanf(buf, "%d", &load) != 1)
{
  fprintf(stderr, "Can't get load value\n");
  return(1);
}

while(fgets(buf, 512, fp)!=NULL)
{
  if(sscanf(buf, "%s %d %d", garbage, &weight, &value) != 3)
  {
    fprintf(stderr, "Couldn't parse line '%s'\n", buf);
    continue;
  }

  do_stuff();
}

You'll get purists complaining about scanf and its dangers but its far preferable to building your own integer-parsing routines. Used in this fashion it is fairly safe, with no risk of buffer overflows and none of the strange half-a-line-eaten problems plain scanf is infamous for.