一：变量的赋值和变量的初始化问题
变量赋值和变量初始化不是一回事！
变量赋值发生在运行期，其写法遵循赋值语法规定。
变量初始化发生在编译期或运行期，其写法遵循初始化列表语法规定。
局部变量是在函数内部所以它既可以初始化也可以赋值。
#include<stdio.h> #include<string.h> typedef struct Fil{ char *homework; // 需要申请内存，否则会报错。 int num; char teacher[50]; }file; file homework; homework.num=4; homework.teacher="Ms zhang"; int main() { printf("the homework is %s,the num is %d.",homework.teacher,homework.num); return 0; }
报错原因："[Error] expected ‘=‘, ‘,‘, ‘;‘, ‘asm‘ or ‘__attribute__‘ before ‘.‘ token"
file homework；语句中已经把homework中的成员变量初始化了，因为全局变量如果不显式初始化的话 会自动初始化为0。在给成员变量赋值的时候只能在函数内，所以会报错。
二：字符指针赋值问题
#include<stdio.h> #include<string.h> typedef struct Fil{ char *homework; // 需要申请内存，否则会报错。 int num; char teacher[50]; }file; int main() { file homework; homework.homework="english"; // 不能直接赋值 homework.num=4; homework.teacher="Ms zhang"; printf("the homework is %s,the num is %d,the teacher is %s.",homework.homework,homework.num,homework.teacher); return 0; }
问题：1.在结构体中给指针赋值时不能直接赋值，而应该先分配内存，再赋值。homework.homework=(char*)malloc(sizeof(char)*8);
2.在结构体中给指针和数组赋值时，不能直接赋值，应该用strcpy()函数。
三：正确的赋值和初始化
#include<stdio.h> #include<string.h> typedef struct Fil{ char *homework; // 需要申请内存，否则会报错。 int num; char teacher[50]; }file; file housework={"chinese",2,"Li Qi"}; // "[Error] expected ‘=‘, ‘,‘, ‘;‘, ‘asm‘ or ‘__attribute__‘ before ‘.‘ token"这句其实已经把成员初始化为0了,因为全局变量如果不显式初始化的话 会自动初始化为0
int main() { file homework; homework.homework=(char*)malloc(sizeof(char)*8); // 结构体中字符串在堆上申请内存然后再赋值 strcpy(homework.homework,"english"); homework.num=4; strcpy(homework.teacher,"Ms zhang"); printf(" the homework is %s\n the num is %d\n the teacher is %s\n",homework.homework,homework.num,homework.teacher); printf(" the housework is %s\n the num is %d\n the teacher is %s\n",housework.homework,housework.num,housework.teacher); return 0; }
原文：https://www.cnblogs.com/ligei/p/12486363.html