get and check Strings in c language

Question

I tried to write program that scan a string from user and check it what the user input and if it is true do somthing and if it's not do somthing else. the code i wrote is like this:

#include<stdio.h>
#include<conio.h>

int main()
{
    char string[20];
    printf("Enter a sentence : ");
    scanf("%s",&string);
    if(strcmp(string,"what's up")==0)
        printf("\nNothing special.");
    else
        printf("\nYou didn't enter correct sentence.");
    getch();
    return 0;
}

but it doesn't work correct.I think because the program can't recognize the space when it want to scan.What should i do?(I'm new to c,so please explain what did you do.)

change scanf("%s",&string); to scanf("%19[^\n]", string); also you need #include <string.h> — BLUEPIXY
– BLUEPIXY, Commented Oct 15, 2015 at 9:22
scanf needs other formats to be able to read input containing white-space. — Some programmer dude
– Some programmer dude, Commented Oct 15, 2015 at 9:22

Gopi · Accepted Answer · 2015-10-15 09:22:29Z

3

%s format specifier can't be used to scan a string with space.

You need to use fgets()

size_t n;
fgets(string,sizeof(string),stdin);
n = strlen(string);
if(n>0 && string[n-1] == '\n')
string[n-1] = '\0';

PS: fgets() comes with a newline character.So you need to gently remove it as shown above

answered Oct 15, 2015 at 9:22

Gopi

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machine_1 · Accepted Answer · 2015-10-15 09:57:49Z

2

you can still use scanf but like this :

#include<stdio.h>
#include<conio.h>

int main()
{
    char string[20];
    printf("Enter a sentence : ");
    scanf(" %[^\n]s",string);
    if(strcmp(string,"what's up")==0)
        printf("\nNothing special.");
    else
        printf("\nYou didn't enter correct sentence.");
    getch();
    return 0;
}

To prevent buffer overflow,you can write scanf(" %19[^\n]s",string);

edited Oct 15, 2015 at 9:57

answered Oct 15, 2015 at 9:44

machine_1

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Comments

Jay Dabhi · Accepted Answer · 2015-10-15 11:02:36Z

0

you can use the getline1() function to get the entire line as shown below:

 /* getline1: read a line into s, return length*/
    int getline1(char s[],int lim)
    {
    int c, i;
    for (i=0; i < lim-1 && (c=getchar())!=EOF && c!='\n'; ++i)
    s[i] = c;
    if (c == '\n') {
    s[i] = c;
    ++i;
    }
    s[i] = '\0';
    return i;
    }

lim specifies the maximum length of the line.

answered Oct 15, 2015 at 11:02

Jay Dabhi

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