How can I change the size of Array?(and how can I throw the trash values of Array?)

Question

Hi I wrote a program below. It's a program, that saves the letters backwards in an Array, when the user gives a string.


int main(){

    char string[100];
    char gnirts[100];

    int i, j;

    printf("String : ");
    scanf("%s", string);

    int size = sizeof(string)/sizeof(char);

    for(i=size-1, j=0; 0<=i ; i--, j++){
        gnirts[j] = string[i]; 
    }

    for(i=0; i<size; i++){
        if(gnirts[i])
            printf("%c", gnirts[i]);
    }

    return 0;
}

I gave the program String : asdf and received �i��i��i�fdsa

At the beginning I set the size of string as 100. And then with the line int size = sizeof(string)/sizeof(char); I set Array string with the size, that depends on what the User gives. But it's not working. I got a trash values before the meaningful values.

How can I delete the trash values and set a new size of the Array string and get the right result?

Thank you.

`size` will always be `100`, since it's based on the array's declared size, not the input length. — Barmar, Nov 08 '21 at 18:38
To add on to what the others have said already, all strings in C end with 0 ('\0') so you could loop through until you find the 0 at the end. Also when copying the array you should place said 0 at the end. — badProgrammer0123456, Nov 08 '21 at 18:45

score 0 · Accepted Answer · answered Nov 08 '21 at 18:39

0

sizeof(string) gives you the size of the entire array in bytes, not the number of characters in the string.

To get the length of the string, you want strlen:

int size = strlen(string);

answered Nov 08 '21 at 18:39

dbush

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Thank u! It works! – salami2 Nov 08 '21 at 18:53
@salami2 Glad I could help. Feel free to [accept this answer](https://stackoverflow.com/help/accepted-answer) if you found it useful. – dbush Nov 08 '21 at 18:54

How can I change the size of Array?(and how can I throw the trash values of Array?)

1 Answers1