strings in C

[dapper belfry]

i set the string length to 5 and tried to store 5 characters in it, but why does it say the length is 7 in output?

[olive crescent]

<@&987246683568103514> please have a look, thanks.

[olive crescent]

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[dapper belfry]

also the last 2 letters are garbage values? since they are random every time i run the program
'u' and 'j' here

[smoky brook]

u have undefined behavior here

ur strings are incorrect

in c, arrays dont know their length

so how does strlen work? how does it know where the text ends?

it goes until it finds the magic value \0

the null-terminator

in ur program, it seems it found one 2 spots after the string

so it printed up to there

but it could be anywhere or nowhere. its undefined behavior and pure coincidence that there was a \0 in memory there

sooo... how to do it proper? ur array has to have 6 spots, not 5. and the last char should be '\0'

then it works

[bleak basin]

Shouldn't a string literal automatically add the \0 ?

[scenic vortex]

it does but length is 5 of the array..

better way is char str[] = "apple", let compiler do it

#include <stdio.h>
#include <string.h>
int main(){
  char str1[6] = "apple";
  printf("%s \n",str1);
  printf("Length of the sting is %d \n",strlen(str1));
  for(int i = 0; str1[i] != 0; i++)
    printf("%c \n",str1[i]);
  return 0;
}

[olive crescent]

Detected code, here are some useful tools:

Formatted code

#include<stdio.h> #include<string.h> int main() {
  char str1[6]  = "apple";
  printf("%s \n", str1);
  printf("Length of the sting is %d \n", strlen(str1));
  for (int i = 0; str1[i]  != 0; i++) printf("%c \n", str1[i] );
  return 0;
}

[dapper belfry]

yes but what if i want an array of characters and not a string?

oh i guess then i cant use the strlen

[smoky brook]

exactly

any of the string methods will assume the end is marked by the null terminator

[dapper belfry]

how is that possible

[smoky brook]

some of the methods also have an overload where u can explicitly tell it the length manually, so that it can also work with strings without null terminator

[dapper belfry]

oh its weird behaviour cuz strlen() was expecting a string?

[smoky brook]

it just read the memory beyond ur array and by coincident, there was a 0 byte there, 2 spots later

pure coincident

remember that c has no safety features here. it just reads the memory beyond ur array

[dapper belfry]

i ran it again

how is it still 7?

i ran it a few times its always 7?

maybe the "0" byte is still at that memory location until i over write it?

[smoky brook]

it could be sth else in ur code sitting there

in any case, it's undefined behavior

and UB doesn't necessarily mean that it's random

[dapper belfry]

oh

noted , thanks!

also why does it says 'unmatched' is not initialized?

[smoky brook]

mind sharing the code as formatted text, not image

then we can try ourselves

btw, u should avoid that comma thing

int end, count = 0;

not even sure it works the way u want

wouldn't be surprised if end is not initialized here