CODEWITHSUNDEEP
cstring
Fenil
Fenil

Reputation: 396

Question mark at end of printf

Here is a simple code of reversing the string in C the last printf statement prints the reverse order , but with a question mark at the end, while I just want to print the reversed string not the question mark How do I fix it?

#include<stdio.h>
#include<string.h>
int main(){
char new_string[100];
char string[100];
scanf("%s",string);
printf("original_number = %s\n",string);
int i;
int l = strlen(string)-1;

for(i = 0; i<=l; i++){
 new_string[i] = string[l-i];
 printf("%c\n",new_string[i]);
    }
 printf("rev_number = %s\n",new_string);
}

input : abcd

output: original_number = abcd

d

c

b

a

rev_number = dcba?

Upvotes: 1

Views: 12179

Answers (4)

VolAnd
VolAnd

Reputation: 6407

If the question is "How to add '?' to the end of string?" I have to answers:

1) use strcat to add one more character, e.g.:

#include<stdio.h>
#include<string.h>
int main(){
    char new_string[101] = {0}; // +1 to be sure that enough place for '?' will be available
                                // {0} to init empty string
    char string[100];
    scanf("%s", string);
    printf("original_number = %s\n", string);
    int i;
    int l = strlen(string) - 1;
    for (i = 0; i <= l; i++){
        new_string[i] = string[l - i];
        printf("%c\n", new_string[i]);
    }
    strcat(new_string, "?");
    printf("rev_number = %s\n", new_string);
}

2) put ? and add character \0 after the loop end, e.g.:

#include<stdio.h>
#include<string.h>
int main(){
    char new_string[101]; // +1 to be sure in place for '?'
    char string[100];
    scanf("%s", string);
    printf("original_number = %s\n", string);
    int i;
    int l = strlen(string) - 1;
    for (i = 0; i <= l; i++){
        new_string[i] = string[l - i];
        printf("%c\n", new_string[i]);
    }
    // add one more char
    new_string[i] = '?';
    // set the string end
    new_string[i + 1] = '\0';
    printf("rev_number = %s\n", new_string);
}

Pay attention, that if you fill all the array with 0 as char new_string[101] = {0};, you do not need to add end of string with new_string[i + 1] = '\0';, so the second variant can be shorter if initialization is as in the first one

For both snippets I have the same output

enter image description here

UPDATE:

One more advice on working with strings. When input is made with scanf and you know how much characters can be stored in your array of chars use the following approach to prevent violation of the array boundaries

char string[10]; // if you have 10 bytes 
scanf("%9s", string); // ask not more than 9 characters

remember that you need one more byte for '\0' (null terminator).

Upvotes: 0

Hemanth
Hemanth

Reputation: 1

terminate new_string by new_string[i]='\0' after for-loop

Upvotes: 0

Kishan Oza
Kishan Oza

Reputation: 1735

the problem is you are taking "end of string" as the last input in for loop.you do not need the variable "l". you can do some think like that

int main()
{
    char new_string[100];
    char string1[100];
    scanf("%s",string1);
    printf("original_number = %s\n",string1);
    int i;


    for(i = 0; i<=strlen(string1); i++){
     new_string[i] = string1[i-1];

     printf("%c\n",new_string[i]);
        }
     printf("rev_number = %s\n",new_string);
}

Upvotes: -1

Rishi
Rishi

Reputation: 1395

You need to null terminate your string. Add this line at after the for loop where you reverse string.

new_string[i]='\0';

for(i = 0; i<=l; i++){
   new_string[i] = string[l-i];
   printf("%c\n",new_string[i]);
}
new_string[i]='\0'; // add this 
printf("rev_number = %s\n",new_string);

check-here

Upvotes: 5

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