Reputation: 309

Redundant characters in string, c

I'm trying to get selected characters from one string into another. Everything looks okay, except the program keeps adding additional characters to the output. And it seems that it tends to add different number of these "unecessary" characters. Where might the problem be?

int main(void) {
    int i,j=0;
    char string[256];
    char second_arr[256];
    scanf("%255s", string);

    for(i=0;i<256;i++){
        if(string[i]=='('||string[i]=='['||string[i]=='{'){
            second_arr[j]=string[i];
            j++;
        }
    }
    printf("%s", second_arr);
}

Say,

input: (hello)(}[} --->
Output:(([[H

Upvotes: 0

Answers (4)

Carey Gregory

Reputation: 6846

Problem 1: You're not testing scanf for failure. It can return EOF, or zero to indicate the input didn't match your format string.

Problem 2: You're copying all 256 chars even if the user entered fewer, which means you're copying junk.

Problem 3: You're not adding a null terminator to second_arr.

Just do this:

if (scanf("%255s", string) != 1)
{
    printf("scanf failed\n");
    return 1;
}

for (i = 0; i < 256 && string[i]; i++) {
    if(string[i]=='('||string[i]=='['||string[i]=='{'){
        second_arr[j]=string[i];
        j++;
    }
}
second_arr[j] = '\0';
printf("%s", second_arr);
return 0;

Upvotes: 2

barak manos

Reputation: 30136

Try this:

for (i=0; string[i]!=0; i++) // iterate the input string until the null-character
{
    if (string[i] == '(' || string[i] == '[' || string[i] == '{')
        second_arr[j++] = string[i];
}
second_arr[j] = 0; // set a null-character at the end of the output string

Upvotes: 1