sscanf

[topaz edge]

Hey, I'm currently trying to do a project, I have in a file.txt the info of several people, each line has their age, name and gender (Ex: 18,Paul Walker,Male), I'm trying to just print the age and name of the person if they are male and just the name if they are female.

I did:

fgets(line, 200, file); //to get each string from the file.txt
sscanf(line, "%d,%[^,],%[^,]", &age, name, gender); //store each value in a variable 

however when I tried to do:

if(gender == "male"){
     printf("%d, %s\n", age, name);
} else if(gender == "female") {
     printf("%s\n", name);
}

to try to just show their name if they are female and the name + age if they are male, it doesen't work, how do I fix this? And then with the info that I just printed, how do I create a seperate file and put it in there?

[remote seal]

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.

[topaz edge]

Updated ^^^^^^^^^^^^

[mossy knot]

You cannot compare strings using ==.
That would be a pointer comparison.
You really want to use strcmp().

[topaz edge]

I tried it but it doesen't work

[mossy knot]

if (strcmp(gender, "male") == 0) {}

Should have mentioned that strcmp() returns 0 if the strings match.

[topaz edge]

I did:

char male[] = "male";
int result;

result = strcmp(male, gender);

printf("%d ---> %s", result, gender);

and the output was:

1 ---> male
1 ---> female
.
.
.

just to test it out, seeing as it wasn't working

[mossy knot]

Maybe gender is not null terminated. Try:

strncmp(gender, "male", 4)

[topaz edge]

the 4 is for the size of the char gender?

[mossy knot]

Yeah, so it compares the first 4 characters of each.

[topaz edge]

ok 4 without the null so, that would 6 for female and 4 for male

[mossy knot]

Yep, the issue of course if gender were to read "malevolent".

[topaz edge]

yh

that's the problem

cause gender will read

female

and male

but I can't even

add the 4

it says too many arguments to call

[mossy knot]

strncmp()
Note the little 'n' there

[topaz edge]

ah, mb

it has worked

that was it

[mossy knot]

Hang on.
Counter suggestion, if I may.

[topaz edge]

mhm

[mossy knot]

Try

char gender[10] = { 0 }; // or whatever size gender is in your code

Then go back to plain strcmp().
I think you may find this works.

[topaz edge]

nope

[mossy knot]

🤔

How does your code declare gender?

[topaz edge]

I have a file.txt

with lines

each line has "19,Paul Walker,Male" and so on

I just did fgets

and sscanf

[mossy knot]

;compile

#include <stdio.h>
#include <string.h>

int main()
{
  char* line = "10,fred,male,something";

  int age = 0;
  char gender[200] = { 0 };
  char name[200] = { 0 };

  if (sscanf(line, "%d,%199[^,],%199[^,]", &age, name, gender) == 3) {
    if (strcmp(gender, "male") == 0) {
      puts("male");
    }
    else {
      puts("not male");
    }
  }
}

Note the %9[^,]
Those are 1 less than the size of the placeholder strings. That prevents you from reading beyond the buffer AND ensures that these strings are always NULL terminated.

[scarlet plaza]

Program Output

male

Lord Dimwit Flathead#1478 | 41ms | c | x86-64 gcc 12.2 | godbolt.org

[topaz edge]

I did all of that

I didn't use the 9 tho

I just did %[^,]

[mossy knot]

char name[10] = { 0 };
// scan as %9[^,]

If the buffer was 20, then scan as %19[^,].
I.e. always one less than the buffer size.

[topaz edge]

well the thing is the name varies

and the size of the name varies

so I can't really do that

or I'll eat other people's names

[mossy knot]

How are name and gender declared in your code?

[topaz edge]

char name[200];
char gender[200];

to make sure it fits either way

cause no one will have a name that takes over 200 characters

I'm still in the basics of C, I've started uni like 2 months ago

So I'm not worried about memory yet

And optimizing

[mossy knot]

There you go.
So scan as %199[^,]

The 199 is a maximum.
See revised program I wrote above.

[topaz edge]

why did you do the if sscanf(......) == 3

?

to make sure it always gets at least 3 variables

[mossy knot]

Because you are extracting 3 params

[topaz edge]

ah ok

[mossy knot]

If you didn't get three, then that line is wrong, or empty.

[topaz edge]

mhm

It's working now

I just have to move on to the next problem lol

[mossy knot]

NP

[topaz edge]

👍

!solved