The progress run smoothly without touching "gets" function and idk why

Question

I got headache because of this code (I already known 'about the dangers of "gets" function, but still want to use it).

I'm using Code::Blocks, F9->type '1', enter->the progress runs pass gets function, and does not let me type the input.

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

int ngat()//stop function
{
    int thoat;
    printf("\nNhap '1' de tiep tuc hoac '0' de thoat: ");//1:continue,0:exit
    scanf("%d",&thoat);
    switch(thoat)
    {
        case 1:main();
        case 0:break;
    }
}

void upper(char s1[])
{
    int i=0;
    while(s1[i]!='\0')
    {
        if (s1[i] >= 'a' && s1[i] <= 'z')
        {
         s1[i] = s1[i] - 32;
        }
        i++;
    }
}

int main()
{
    system("cls");
    puts("1.Viet ham upper (doi ki tu sang ki tu hoa)\n2.Viet ham lower (doi ki tu sang ki tu thuong)\n3.Viet ham proper (doi ki tu dau sang ki tu hoa");
    int sobai;
    printf("\nNhap so cua bai: ");
    scanf("%d",&sobai);
    switch(sobai)
    {
        case 1:
        {
            system("cls");
            char s1[255];
            printf("\nViet ham upper (doi ki tu sang ki tu hoa)");//string upper function
            printf("\nNhap xau:");//input string
            gets(s1);
            upper(s1);
            printf("%s\n",s1);
            ngat();
            break;
        }
    }
}

Mixing `scanf` and `fgets` (or `gets`, if you insist) never works. Do a web search on "skips fgets after scanf", you'll get lots of answers. — Steve Summit, May 05 '18 at 02:19
Possible duplicate of [scanf() leaves the new line char in the buffer](https://stackoverflow.com/questions/5240789/scanf-leaves-the-new-line-char-in-the-buffer) — Steve Summit, May 05 '18 at 02:21
solved my problem from this site: https://stackoverflow.com/questions/22226529/program-doesnt-execute-gets-after-scanf-even-using-fflushstdin — Vĩnh Thịnhh, May 05 '18 at 02:31
does this site have some kind of thump up icon, i want to thank u @SteveSummit — Vĩnh Thịnhh, May 05 '18 at 02:32

score 0 · Answer 1 · answered May 05 '18 at 02:30

0

The problem with above code is scanf() reads an integer and leaves a newline character in buffer. So gets() only reads newline and the string that you expect is ignored by the program.

How to solve this problem?

make scanf() to read a new line by using an extra “\n”, i.e., scanf(“%d\n”, &sobai) . In fact scanf(“%d “, &sobai) also works (Note extra space).
add a getchar() after scanf() to read an extra newline.

answered May 05 '18 at 02:30

Abhishek Keshri

3,074
14
31

i've just got the answer by placing getc(stdin) after scanf(), thank u tho :) – Vĩnh Thịnhh May 05 '18 at 02:36

The progress run smoothly without touching "gets" function and idk why

1 Answers1