some fgets cannot work in C programming

Question

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

int main()
{
    int sel_1, sel_2, telno[12], price = 0, sum = 0, i;
    char pkg[2], name[10], addrs[30], name_1[50][50], addrs_1[50][50];

    printf(" Lunch4You Enterprise\n Delivery Service Subscription System\n");
    printf("==========================================================================");
    printf("\nPackage that we have:\n 1. Package A: 20days/month(5days/week) - RM60/month");
    printf("\n 2. Package B: 12days/month(3days/week) - RM45/month");
    printf("\n 3. Package C: 8days/month(2days/week) - RM35/month");

    do
    {
        printf("\nPlease select the package: ");
        scanf("%d", &sel_1);
    }
    while (sel_1 != 1 && sel_1 != 2 && sel_1 != 3);

    switch (sel_1)
    {
        case 1: strcpy(pkg, "A"); price = 60;
                break;
        case 2: strcpy(pkg, "B"); price = 45;
                break;
        case 3: strcpy(pkg, "C"); price = 35;
                break;
    }

    printf("\n\nYou have selected Package %s.", pkg);

    do
    {
        printf("\nHow many receiver of lunchbox?: ");
        scanf("%d", &sel_2);
    }
    while (sel_2 > 5 || sel_2 < 1);

    sum = sel_2 * price;
    printf("\n\nPlease enter the information below:\nName of subscriber: ");
    scanf("%s", &name);
    printf("\nAddress (Pick-up): ");
    fgets(addrs,30,stdin);

    for (i = 0; i < sel_2; ++i)
    {
        printf("Name of receiver (%d): ", i + 1);
        fgets(name_1[i], 50, stdin);
        printf("Address(Receiver)(%d): ", i + 1);
        fgets(addrs_1[i], 50, stdin);
        printf("Tel No (%d)", i + 1);
        scanf("%d", &telno[i]);
    }

    printf("\n\nYour information for lunchbox delivery are:");
    printf("\nPackage : %s", pkg);
    printf("\nPick-up Address: %s", addrs);

    for (i = 0; i < sel_2; ++i)
    {
        printf("\nReceiver %d: %s, %s\n\t\t%d", i + 1, name_1[i], addrs_1[i], telno[i]);
    }
    printf("\n\nTotal fee: RM%d\n", sum);

    return 0;
}

$some fgets cannot work, it just skip to the next fgets then wait for users to enter.(in this case, the fgets(addrs) and fgets(name_1) in the 'for loop' cannot work) can I know why and how to solve this problem? thks.

Answer 1

This sequence is a problem:

scanf("%s", &name);
printf("\nAddress (Pick-up): ");
fgets(addrs,30,stdin);

The scanf() stopped at the first white space character, quite probably a newline; the fgets() then reads up to and including the newline, so it doesn't need to wait for any input because there's a newline already in the input buffer, left over from the scanf() call.

You need to read up to the newline after the scanf() . And you should be checking for problems after each input operation.

if (scanf("%s", name) != 1)
    …report error…
while ((c = getchar()) != EOF && c != '\n')
    ;
if (fgets(addrs, sizeof(addrs), stdin) == 0)
    …report error…

Answer 2

You need to end (not start) your printf(3) format string with \\n or to call fflush(3) since stdio(3) is usually buffered (see setvbuf(3) ...); so add a fflush(NULL); before every call to scanf .

You should also test the return (scanned items) count of scanf(3) .

Read also documentation of fgets(3) . You may prefer to use getline(3) or even (on systems having it, like Linux) readline(3)