Every time I run this code, I get 3. But it should be 10. How to fix it?

Question

1.00/5 (2 votes)

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

int main()
{
    int n;
    char* element[] = "Hydrogen" ,"Helium", "Lithium", "Beryllium", "Boron", "Carbon", "Nitrogen", "Oxygen", "Fluorine", "Neon" };
    n=strlen(element);
    printf("%d",n);
    return 0;
}

What I have tried:

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

int main()
{
    int n;
    char* element[] = {"Hydrogen","Helium","Lithium","Beryllium","Boron","Carbon","Nitrogen","Oxygen","Fluorine","Neon"};
    n=strlen(element);
    printf("%d",n);
    return 0;
}

Posted 24-Mar-17 19:16pm

Zarif Muhtasim

Updated 25-Mar-17 3:38am

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Comments

Garth J Lancaster 25-Mar-17 2:08am

I suspect I know the answer, but, for completeness, do you wish to know how many elements are in the element array, for which 10 would be correct, vs the size (number of characters) of the first element

obviously, the issue in your code, is that

n=strlen(element);

isnt doing quite what you expect/think its doing ....

[edit]
I'll toss this out there for you to think about - have you looked at the sizeof() function ?
have a look at sizeof(element) and sizeof(element[0])
[/edit]

3 solutions

Solution 2

If you look at the definition of strlen: strlen - C++ Reference[^] it takes a parameter which is a pointer to a char - or a string in other words - and returns the number of characters up to the first null value.
That isn't what to are passing it: element is an array of pointers to char -or an array of strings. So it looks at the array as if it was a string, and gets it horribly wrong.

Pass it one of the elements of the array, and it'll return what you want!

n=strlen(element[0]);

Or

n=strlen(element[1]);

...

Posted 24-Mar-17 20:23pm

OriginalGriff

Solution 3

The size of an array is known at compile time. Usually a macro like the following is used

C++

#define NELEM(a)  (sizeof(a) / sizeof(a[0]))

Try, for instance

C

#include <stdio.h>

#define NELEM(a)  (sizeof(a) / sizeof(a[0]))

int main()
{
    int n;
    char* element[] = { "Hydrogen" ,"Helium", "Lithium", "Beryllium", "Boron", "Carbon", "Nitrogen", "Oxygen", "Fluorine", "Neon" };
    n = NELEM(element);
    printf("%d\n",n);
    return 0;
}

Posted 25-Mar-17 3:38am

CPallini

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sarvesh.upadhyay · Accepted Answer · 2017-03-24T20:17:00

Solution 1

We can not use strlen to get the count of elements in an array.

I have solved for you and linked as below.

length of an array of strings[^]

Posted 24-Mar-17 20:17pm

sarvesh.upadhyay

Updated 24-Mar-17 20:39pm

v3

Comments

Richard MacCutchan 25-Mar-17 9:43am

If you know the answer then post the code here, not on another website.