scanf()后程序终止问题排查：结构体实现新生儿信息录入异常

问题描述 #

开发采用结构体实现的新生儿信息录入C程序时，程序在打印“Father age”输入提示后直接终止，程序输出如下：

原代码 #

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

struct father{
    char dad_name[50];
    int dad_age;
};
struct mother{
    char mom_name[50];
    int mom_age;
};
struct baby{
    char baby_name[50];
    char sex[6];
    char birthday[10];

    struct father father1;
    struct mother mother1;
};

struct baby *b1;
void display(int);

int main(){
    int baby_num;

    printf("Enter number of baby that is/are going to input: ");
    scanf("%d", &baby_num);

    display(baby_num);

    printf("\nNEW BORN IN KUANTAN HOSPITAL\n");
    for(int i=0; i<baby_num; i++){
        printf("\nBaby %d\n", i+1);
        printf("Baby Name: %s\n", b1[i].baby_name);
        printf("Sex: %s\n", b1[i].sex);
        printf("Birthday: %s\n", b1[i].birthday);
        printf("\nFather name: %s\n", b1[i].father1.dad_name);
        printf("Father age: %d", b1[i].father1.dad_age);
        printf("\nMother name: %s\n", b1[i].mother1.mom_name);
        printf("Mother age: %s\n", b1[i].mother1.mom_age);
    };
    return 0;
};

void display(int baby_num){
    int temp;

    b1 = (struct baby*) malloc(baby_num * sizeof(struct baby));
    for(int i=0; i<baby_num;i++){
        printf("Baby Name: ");
        scanf("%d", &temp);
        scanf("%[^\n]", b1[i].baby_name);
        printf("Sex: ");
        scanf("%s", b1[i].sex);
        printf("Birthday: ");
        scanf(" %s", b1[i].birthday);
        printf("Father name: ");
        scanf("%d", &temp);
        scanf("%[^\n]", b1[i].father1.dad_name);
        printf("Father age: ");
        scanf("%d", b1[i].father1.dad_age);
        printf("Mother name: ");
        scanf("%[^\n]", b1[i].mother1.mom_name);
        printf("Mother age: ");
        scanf(" %d", b1[i].mother1.mom_age);
    };
}

异常原因分析 #

1. scanf参数传递错误（核心崩溃原因）
   读取父亲年龄和母亲年龄时，scanf("%d", b1[i].father1.dad_age);和scanf(" %d", b1[i].mother1.mom_age);未传入变量地址。%d格式要求接收int*类型参数，直接传int变量会导致非法内存访问，触发程序崩溃。

2. 输入缓冲区处理混乱
   用scanf("%d", &temp);清除缓冲区换行的逻辑无效且多余，scanf("%[^\n]")会读取到缓冲区残留的换行符，导致字符串读取异常，干扰后续输入流程。

3. 输出格式不匹配
   打印母亲年龄时使用%s格式符对应int类型的mom_age，格式不匹配会导致输出乱码或未知行为。

解决方法 #

1. 修复scanf地址传递问题
   读取年龄时必须传入变量地址，修改为：

   scanf("%d", &b1[i].father1.dad_age);
   scanf("%d", &b1[i].mother1.mom_age);
   

2. 正确处理输入缓冲区换行符
   去掉多余的scanf("%d", &temp);，在scanf("%[^\n]")格式串前加空格，自动跳过缓冲区中的空白字符（包括换行）：

   printf("Baby Name: ");
   scanf(" %[^\n]", b1[i].baby_name);
   printf("Father name: ");
   scanf(" %[^\n]", b1[i].father1.dad_name);
   printf("Mother name: ");
   scanf(" %[^\n]", b1[i].mother1.mom_name);
   

3. 修正输出格式
   打印母亲年龄时改用%d格式符：

   printf("Mother age: %d\n", b1[i].mother1.mom_age);
   

4. 优化内存管理（可选）
   避免全局指针滥用，将b1改为在main中分配后传递给display函数，并在程序结束后释放内存，防止内存泄漏。

修正后的完整代码 #

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

struct father{
    char dad_name[50];
    int dad_age;
};
struct mother{
    char mom_name[50];
    int mom_age;
};
struct baby{
    char baby_name[50];
    char sex[6];
    char birthday[10];

    struct father father1;
    struct mother mother1;
};

void display(struct baby*, int);

int main(){
    int baby_num;
    struct baby *b1 = NULL;

    printf("Enter number of baby that is/are going to input: ");
    scanf("%d", &baby_num);

    b1 = (struct baby*) malloc(baby_num * sizeof(struct baby));
    if(b1 == NULL){
        printf("Memory allocation failed!\n");
        return 1;
    }

    display(b1, baby_num);

    printf("\nNEW BORN IN KUANTAN HOSPITAL\n");
    for(int i=0; i<baby_num; i++){
        printf("\nBaby %d\n", i+1);
        printf("Baby Name: %s\n", b1[i].baby_name);
        printf("Sex: %s\n", b1[i].sex);
        printf("Birthday: %s\n", b1[i].birthday);
        printf("\nFather name: %s\n", b1[i].father1.dad_name);
        printf("Father age: %d\n", b1[i].father1.dad_age);
        printf("Mother name: %s\n", b1[i].mother1.mom_name);
        printf("Mother age: %d\n", b1[i].mother1.mom_age);
    };

    free(b1);
    return 0;
};

void display(struct baby *b1, int baby_num){
    for(int i=0; i<baby_num;i++){
        printf("Baby Name: ");
        scanf(" %[^\n]", b1[i].baby_name);
        printf("Sex: ");
        scanf("%s", b1[i].sex);
        printf("Birthday: ");
        scanf("%s", b1[i].birthday);
        printf("Father name: ");
        scanf(" %[^\n]", b1[i].father1.dad_name);
        printf("Father age: ");
        scanf("%d", &b1[i].father1.dad_age);
        printf("Mother name: ");
        scanf(" %[^\n]", b1[i].mother1.mom_name);
        printf("Mother age: ");
        scanf("%d", &b1[i].mother1.mom_age);
    };
}

内容的提问来源于stack exchange，提问作者Alpha Chong