String and for loop [duplicate] - c

Question

This question already has answers here:
scanf() leaves the newline character in the buffer
(7 answers)
Closed 4 years ago.
I wrote this C program to enter names and ages of 3 people. But the output wasn't my expectation. It was able to enter name and age for the first person, but it wasn't able for second and third persons. Please help.
#include <stdio.h>
#include <string.h>
int main()
{
int i, age;
char name[20];
for(i=0; i<3; i++)
{
printf("\nEnter name: ");
gets(name);
printf("Enter age: ");
scanf(" %d", &age);
puts(name);
printf(" %d", age);
}
return 0;
}

Answer 1

In short: Your 2nd puts is processing the '\n' from your scanf.
Fix by adding getchar(); after scanf
Explanation:
1st iteration:
printf("\nEnter name: ");
gets(name); // line is read from input
printf("Enter age: ");
scanf(" %d", &age); // a number is read from input, and the newline char ('\n') remains in buffer
puts(name);
printf(" %d", age);
2nd iteration:
printf("\nEnter name: ");
gets(name); // previously buffered newline char is read, thus "skipping" user input
printf("Enter age: ");
scanf(" %d", &age);
puts(name);
printf(" %d", age);
Same goes for 3rd iteration, and this is why you lose user input

Answer 2

The best way to store information of more than one person is to use struct, like
struct person {
int age;
char name[20];
};
and make array of struct, like
struct person people[3];
than use loop with accessing people[i].age and people[i].name, e.g.:
#include <stdio.h>
#include <string.h>
struct person {
int age;
char name[20];
};
#define ARR_SIZE 3
int main(int argc, char* argv[])
{
struct person people[ARR_SIZE];
int i;
char *lastpos;
for(i = 0; i < ARR_SIZE; i++)
{
printf("\nEnter name: ");
scanf(" %s", people[i].name);
if ((lastpos=strchr(people[i].name, '\n')) != NULL) *lastpos = '\0'; // remove newline from the end
printf("Enter age: ");
scanf(" %d", &people[i].age);
}
printf("This is the people you entered:\n");
for(i = 0; i < ARR_SIZE; i++)
{
printf("%d : %s : %d\n", i+1, people[i].name, people[i].age);
}
return 0;
}
UPDATE:
As you see I use scanf(" %s", people[i].name); instead of gets(people[i].name); to read name from stdin. Try both option for the following cases:
enter short name (e.g. John) and correct age (e.g. 15)
enter two word name (e.g. John Smith) and correct age (e.g. 17)
enter short name and uncorrect age (e.g. five)
Then read articles about value returned by scanf and cleaning input buffer