在 C 中创建和打印基于指针的结构

Question

我刚刚开始学习结构，我已经能够让它们在使用常规变量时正常工作。但是，当我尝试使用指针执行此操作时，我的程序将运行但会崩溃。我确定我只是出了点小问题......

struct Student{
char firstName[30];
char lastName[30];
float gpa;
int id;
};


int main()
{
struct Student *student;
student = (struct Student*)sizeof(struct Student);
strcpy(student->firstName,"Marlop");
strcpy(student->lastName,"smiitlh");
student->gpa = 4.54;
student->id = 45893;

printf("%s",student->firstName);

return 0;
}

Answer 1

这段代码

student = (struct Student*)sizeof(struct Student );

没有意义。这是为 student 分配一些(无效的很可能)无意义的地址。

您应该使用malloc() 来分配一些内存。试试这个:

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

struct Student{
    char firstName[30];
    char lastName[30];
    float gpa;
    int id;
};


int main(void)
{
    struct Student *student;
    student = malloc(sizeof(struct Student));
    strcpy(student->firstName,"Marlop");
    strcpy(student->lastName,"smiitlh");
    student->gpa = 4.54;
    student->id = 45893;

    printf("%s",student->firstName);

    free(student);
    return 0;
}