Problem with gets

[shruthi]

Hello Everyone!
The program is not waiting for me to enter the name,it prints name and address printf statements and then pauses,how do I correct this?

insert

void phone_book(int o)
{
    printf("enter the name\n");
    gets(c[o].name);


    printf("enter the address\n");
    gets(c[o].addr);


    printf("enter the email id \n");
    gets(c[o].e_id);


    printf("enter th phone no\n");
    scanf("%d",&c[o].ph_no);


}

output:
enter the name
enter the address

[GReaper]

The newline remains in the input stream. Try doing a:

while ((c = getchar()) != '\n' && c != EOF);

That should clear the input buffer( c should be "int" ).

EDIT: FAQ > How do I... (Level 1) > Get a line of text from the user/keyboard (C)

[memcpy]

Or just use fgets(). It's much safer and you don't have to worry about newline character issues.

Also, the structure of that program (global struct array that's not a pointer) looks wasteful.

[shruthi]

Thanks for the link Greaper.
fgets is working fine,but before that I use scanf for switch input in the main function and by this even if I use fgets in the above (phone_book) function,it's still printing the two lines together.

insert

int main()
{
    int ch=1;


     printf("PHONE BOOK\n");
        printf("Menu\n");
        printf("1.Write 2.Show 3.Search 4.Edit 5.Exit\n");
        scanf("%d",&ch);     // problem part,when I comment this part,it works smoothly,what else can I use instead of this?
        switch(ch)
        {
            case 1 : phone_book(1);
                        break;
            default : printf("invalid");
                        break;
        }
    return 0;
}

[MK27]

fgets is working fine,but before that I use scanf for switch input in the main function and by this even if I use fgets in the above (phone_book) function,it's still printing the two lines together.

Because when you enter a single char, what you actually enter is two chars -- a letter and '\n' for the return key. Scanf(%c) reads the first one, and as GReaper says, the second one remains in the stdin buffer. Fgets() reads upto and including a '\n', and that's what happens next.

Look at the code suggested in post #2 to deal with this issue, think about how it works, and apply it appropriately.

[shruthi]

The newline remains in the input stream. Try doing a:

while ((c = getchar()) != '\n' && c != EOF);

That should clear the input buffer( c should be "int" ).

EDIT: FAQ > How do I... (Level 1) > Get a line of text from the user/keyboard (C)

Tried using while statement and the stored in variable c was 10 instead of 1,which was the user input,therefore it went to the default statement of the switch case.

[laserlight]

Tried using while statement and the stored in variable c was 10 instead of 1,which was the user input,therefore it went to the default statement of the switch case.

Read GReaper's post again. What is that while loop supposed to do?

[shruthi]

Read GReaper's post again. What is that while loop supposed to do?

Isn't it,variable c should take a value other than '\n' and EOF and when it when it receives '\n' or EOF it exits the while loop?

[laserlight]

You're missing the point: the use of scanf leaves the trailing newline in the input buffer.

The idea then is to remove this newline. There are a few ways, and this while loop is one of them.

[shruthi]

Thanks Everyone I finally solved it with all your help. The mistake I made when I added the while loop was,I used the same variable in scanf and in the while loop,that's why it was not working.When I used two separate variables it worked fine.

[laserlight]

One more thing,the while loop should be without the semicolon at the end,only then it works.

Err... no. That semi-colon is deliberate as the loop body does no other work.

[shruthi]

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void phone_book()
{
    char name[5],addr[6],e_id[7];
    int ph;
    printf("enter the name\n");
    fgets(name,sizeof(name),stdin);


    printf("enter the address\n");
    fgets(addr,sizeof(addr),stdin);


    printf("enter the email id \n");
    fgets(e_id,sizeof(e_id),stdin);


    printf("enter th phone no\n");
    scanf("%d",&ph);


}


int main()
{
    int ch,c;
     printf("PHONE BOOK\n");
        printf("Menu\n");
       printf("1.Write 2.Show c.Search d.Edit e.Exit\n");
       scanf("%d",&ch);
       while ((c = getchar()) != '\n' && c != EOF)
        switch(ch)
        {
            case 1 : phone_book();
                        break;
            default : printf("invalid");
                        break;
        }
    return 0;
}

For some reason,this code is working properly without the semicolon,please have a look.

[GReaper]

Ideally, it works, but try pressing the spacebar a few times after you enter your selection and before hitting enter and observe what happens.

[shruthi]

Sorry for the trouble,but it seems to work even without the semicolon,but I leave it at what GReaper has commented,while loop with semicolon works well.

[shruthi]

Ideally, it works, but try pressing the spacebar a few times after you enter your selection and before hitting enter and observe what happens.

Yeah,I got the point thanks again.