CODEWITHSUNDEEP
cgetchar
Sandra
Sandra

Reputation: 31

why is getchar() inserting additional characters in my input

I want my code to receive an endless stream of input until the user (or text file) returns EOF. The problem is that in both input cases the first character registered is some additional one. Case in point - the input was Applepie, why is the first character registered 'p'?

enter image description here

Code:

string = (char *) malloc(allocated);    

while (c != EOF){

    c = getchar();
    
    if (counter >= allocated -1){
        allocated *= 2;
        new_buffer = realloc(string, allocated ); 
        if (! new_buffer){
            return (char *) string;
        }
        string = new_buffer;
    }
    
    /*store the char*/
    string[counter] = c;
    counter++;
    /*printf("current char: %c\n", string[counter]);*/
}

string[counter] = '\0';

return  (char*)string;

}

Upvotes: 0

Views: 130

Answers (1)

John Bollinger
John Bollinger

Reputation: 181714

Preliminary: why there is a -1 in your string

This has been discussed extensively in comments. It is because getString() writes the EOF indicating the end of the input into the string. It should avoid doing that by checking for EOF before putting the character just read in the string.

Unexpected first character

Case in point - the input was Applepie, why is the first character registered 'p'?

Because of this:

    int counter = 1; /*prints new line every 10 characters*/

[...]

    char c = string[counter];

printAndSum() then proceeds to print c, provided that its value is not -1, so if it prints anything at all then the first character it prints will be the one at index 1. After that, it updates c on each loop iteration with

        c = string[index++];

, which has the effect of starting at the beginning of the string on the second iteration. There are various ways you could fix that, but one of the least disruptive would be to change the initialization of c to

    char c = string[0];  // or string[index]

, and to change the update of c to use preincrement instead of postincrement:

        c = string[++index];

Upvotes: 1

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