结构字符串数组打印最后输入的元素

Question

I want to print all entered elements. Instead, my code prints the most recently entered element twice.

Here is my code:

#include<stdio.h>
void f(struct ar *a);
void d(struct ar *a);
struct ar
{
    char name[50];
};
int main()
{
    struct ar a;
    f(&a);
    d(&a);
}
void f(struct ar *a)
{
    int i;
    for(i=0;i<2;i++)
    {
        printf("enter name:");
        gets(a->name);
    }
}
void d(struct ar *a)
{
    int i;
    for(i=0;i<2;i++)
    {
        puts(a->name);
    }
}

For example:

Input

name:john

name:kendall

Output

kendall

kendall

Answer 1

It's because you are overwriting the value in each iteration.

You can create an array in main() and pass the array to the functions so the values are stored in different places, instead you always pass the same structure instance to gets() and hence overwrite the previous value, so the printing loop prints the same data twice.

The following demonstrate how to pass an array

#include <stdio.h>

struct Data
 {
    char name[50];
 };

void readData(struct Data *array);
void showData(struct Data *array);

int main()
 {
    struct Data array[2];

    readData(array);
    showData(array);
 }

void readData(struct Data *array)
 {
    int i;
    for (i = 0 ; i < 2 ; i++)
     {
        printf("enter name: ");
        fgets(array[i].name, sizeof(array[i].name), stdin);
     }
 }

void showData(struct Data *array)
 {
    int i;
    for (i = 0 ; i < 2 ; i++)
     {
        printf("%s", array[i].name);
     }
 }

Also, don't be lazy when it comes to naming identifiers, even for a simple demonstration they help make the program intent clear and they help you maintain it forever, if you think that doesn't matter, then I am afraid you will have a lot of problems when you work on a real life project.

Answer 2

Here you are taking the inputs twice in same variable. So what the happening is:

• In the first iteration the input is getting stored in ar->name . The first input is john , so ar->name="john"
• In the next iteration the input is also getting stored in ar->name . So if your input is kendall then ar->name="kenadall" .

For this reason the john value is getting overwritten by kendall and when you are printing you are getting the kendall value.

Answer 3

There is a Linked List to do the same thing:

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


struct Data
{
    char name[50];
    struct Data *next;
};

struct Data *readData();
void showData(struct Data *array);

int main()
{
    struct Data *array;

    array = readData();
    showData(array);
}

struct Data *readData()
{
    int i;
    struct Data *tmp = NULL;
    struct Data *head = NULL;
    struct Data *end = head;

    for (i = 0 ; i < 2 ; i++)
    {
        tmp = (struct Data *)malloc(sizeof(struct Data));
        printf("enter name: ");
        fgets(tmp->name, sizeof(tmp->name), stdin);
        if (head == NULL) {
            head = tmp;
        } else {
            end->next = tmp;
        }
        end = tmp;
    }
    return head;
}

void showData(struct Data *array)
{
    int i;
    struct Data *a = array;
    while(a != NULL) {
        printf("%s\n", a->name);
        a = a->next;
    }
}

Answer 4

In the line

gets(a->name);

you are recording the user input to same place each time the for loop runs. Instead, try something like

#include<stdio.h>

struct Name
{
  char first[50];
  char last[50];
};

void recordName(struct Name *name); //writes Name structs
void reportName(struct Name *name); //prints contents of Name structs


int main()
{
  struct Name test_Name;

  recordName(&test_Name);
  reportName(&test_Name);

  return 0;
}

void recordName(struct Name *name)
{
  printf("enter first Name: ");
  fgets(name->first,sizeof(name->first),stdin);

  printf("enter last Name: ");
  fgets(name->last,sizeof(name->last),stdin);
}


void reportName(struct Name *name)
{
  printf("%s%s",name->first, name->last);
}