C beginner help

[abstract kite]

My code:

    int numLines;
    char data[200] = {};
    char *Data = data;
    printf("Enter the number of lines: ");
    scanf("%d", &numLines);

    printf("Enter the integers:\n");
    getchar();
    for (int i = 0; i < numLines; i++) {
        fgets(data, 20, stdin);

        int numbers = strtol(Data, &Data, 10);

        printf("Line %d: has values of: %d ", i + 1, numbers);

}
    return 0;

}

what i want: if I input 4 lines and then when it says enter the integers I want to copy and paste something like this (4 lines of random numbers)

1 2 3 4
25346436 346433 6346436
4363433 346 346 346 ```


I want it to print: Line1 contains values of: 1 2 3 4, line 2 contains values of 1 2 3 4 etc etc

please let me know I am new trying to learn

[lime arch]

When your question is answered use !solved to mark the question as resolved.

Remember to ask specific questions, provide necessary details, and reduce your question to its simplest form. For tips on how to ask a good question run !howto ask.

[real crown]

what's different between that and what you have

[abstract kite]

uh it doesn't work

xd

when inputting this

"1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
"

I get

[real crown]

what's different between that and what you want

[abstract kite]

it should do

from this

"1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16

Line: 1 1 2 3 4

Line 2 5 6 7 8

Line 3

9 10 11 12

but u can see what it does

its weird

[real crown]

and what is that?

[abstract kite]

this

[real crown]

use your words

[abstract kite]

it prints 1 5 6 7 8

which is not even what i put

[real crown]

what do you want it to do?

[abstract kite]

print the correct numbers

[real crown]

what does "correct" mean?

[abstract kite]

the actual nuumbers

that i input

[real crown]

you're only strtoling one number per line

it's doing what you want

[abstract kite]

well obviously i didn't mean to do that

thats what im asking

how do i make it strtol the whole line

[real crown]

you need to call strtol multiple times, one per number

that's what the endptr argument for strtol is for - it'll point to the end of what it just parsed, so you can start there for the next number

it's reading the 1 at the beginning of the first line you pasted in, then printing Line 1: has values of 1, and then the 5 6 7 8 from the second line of what you pasted gets in after that

[abstract kite]

so what should i do

to make it do one line at a time

[real crown]

it is

[abstract kite]

but the first number

in the print

[real crown]

yes

[abstract kite]

is always wrong

[real crown]

no, it's correct

[abstract kite]

by wrong i meant not what i want

[real crown]

then what do you want?

[abstract kite]

bro

[real crown]

we aren't mindreaders

[abstract kite]

i said it like 10 times

wdym u aren't a mind reader

if i input "9 10 11 12
13 14 15 " etc

it should print

line 1: 9 10 11 12

line2: 13 14 15

[real crown]

then you should keep parsing numbers until you reach the end of the line

[abstract kite]

okay how do i do that

[real crown]

by calling strtol multiple times

[abstract kite]

so make a for loop inside the loop?

[real crown]

until endptr is at the end of the line

[abstract kite]

how do i do that

[real crown]

a loop

until endptr reaches the end of the line

[abstract kite]

by end pointer you are referring to &Data

in this case

right

[real crown]

yes, the argument to strtol named endptr

[abstract kite]

for(int x =0; i< ?

what would i be less than

not numlines

wouldn't it be the total amount of numbers per line

[real crown]

.

[abstract kite]

yea

im asking how

im new

[real crown]

and I'm not going to hand you everything on a silver platter

[abstract kite]

so help me understand

because you are repeating urself

[real crown]

how do you think you'd compare endptr to the end of the line

[abstract kite]

idek what ur asking me

[real crown]

do you know what the endptr value is for?

[abstract kite]

yes

for the char

data

&Data

is the second pointer

[real crown]

but do you know what it's actually for

[abstract kite]

all that i know

is whhen using strtol

it takes the first pointer, second pointer, and base

[lime arch]

man7

strtol(3)

strtol, strtoll, strtoq - convert a string to a long integer

Synopsis

#include <stdlib.h>

long strtol(const char *restrict nptr,
            char **restrict endptr, int base);
long long strtoll(const char *restrict nptr,
            char **restrict endptr, int base);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

strtoll():
    _ISOC99_SOURCE
        || /* Glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

[real crown]

I reccomend reading the description of the function, specifically the part that starts with "if endptr is not NULL..."

[abstract kite]

well then ig i dont fully understand how strtol works

because i still dont know

i thought it just takes a string and converts it into integers

[real crown]

the char* you pass a reference to as endptr gets set as a pointer to the first char in the input string that couldn't be converted, aka the first character after the number it parsed

if that first character is the end of the line, then you're done parsing numbers for that line

[tawdry tendon]

It just goes through the string, ignoring all leading whitespace, and then "grabs" digits until any other character, including whitespaces, is encountered.
It then returns you the integer value of the number these digits represent.

If you decided to pass endptr, then strtol will set this pointer to point to the first character after the digits of the number it just converted.