usage of scanf inside while test condition - c

Question

I want to store a series of integers till i press an enter in an array.How can i implement that
Input:
1(tab space)2(tab space)3(tab space)4(tab space)enter
i tried doing this
#include<stdio.h>
main()
{
int i,j,c,d;
int a[5];
for(i=0;i<2;i++){
j=0;
while((d=scanf("%d",&c))==1){
a[j]=c;
j=j+1;
}
}
}
I dont know how scanf works and using scanf return value.Please explain how i can store this input if its not impossible to do so with scanf and also
2)What else can be used inside scanf along with %d ?
I have a file with 200 rows with numbers like this
(NOTE: each row has varied number of values but all numbers are less than 200)
1\t2\t3\t4\t5\t
2\t3\t4\t5\t6\t7\t8\t
11\t12\t13\t
.
.
200
... so i have to store this as an adjacency list representation

Answer 1

For the first part of your question. scanf() returns number of elements successfully read but it is of no use here and you can just scan in a loop and scanf() will pick your integers in a line when you press enter.
#include <stdio.h>
int main(void) {
int a[5];
int i, n;
for(i=0;i<5;i++)
{
if(scanf("%d",&a[i]) != 1)
{
printf("Value not read correctly\n");
break;
}
}
n = i;
for(i=0;i<n;i++)
printf("%d\n",a[i]);
return 0;
}
For the second question you have to do something line
1.Read a line from your file using fgets()
2.Break your line using strtok() with tab as delimiter.
3.Now convert each token to integer using atoi()
4.Now do whatever you want with the integer. i.e. create a node add your integer to the node

Answer 2

Let's make some reasonable assumptions about the width of each row.
These assumptions are useful for simple code, though not needed in general.
#define LINE_WIDTH_MAX 1000
#define INTS_PER_LINE_MAX 100
#define ROWS_PER_FILE (200 /* given by OP */)
Read each row with fgets(), then scan. Could use strtol(), sscanf() or various approaches.
This method uses sscanf() and "%n" to determine when the next number might follow.
int row;
for (row = 0; row < ROWS_PER_FILE; row++) {
char buf[LINE_WIDTH_MAX + 2];
if (fgets(buf, sizeof buf, stdin) == NULL) {
break; // Handle EOF or IO error
}
int num[INTS_PER_LINE_MAX];
char *p = buf;
for (int i = 0; i<INTS_PER_LINE_MAX; i++) {
int n = 0;
if (1 != sscanf(p, "%d %n", &num[i], &n)) {
break;
}
p += n;
}
if (*p) Handle_GarbageInLIne();
// do something with the `i` numbers
}
Notes:
Advise never use scanf()/