C_190418_array

error : variably modified at file scope
help text 1
help text 2

1、#define LISTEN_NUM 10    /*The MAX Number Of Users*/
2、const int LISTEN_NUM = 10;


/*UserProfile Struct, to store user's infomation*/
typedef struct {
char username[10];    /*User Name*/
char userip[20];           /*User IP*/
int isOnline;                /*Is Online*/
} UserProfile;

UserProfile users[LISTEN_NUM];//Users

若用2的方式，则用gcc编译会出现Error： variably modified 'users' at file scope
改成1的形式，则没有报错信息。

原因：
因为由const定义的是变量，用define定义的宏是常量。C++中可以这么用，但是C中不能这么用。

在c里静态数组（固定长度的数组，即LISTEN_NUM位置是常数）是允许的，而动态数组（譬如给数组的长度是用变量来表示的）不能写成UserProfile users[LISTEN_NUM];形式的，只能自行分配内存。

example
notice|待改进 : 无序,当同时满足胜利条件时无法判断先后顺序

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

#define size 3// 3*3
//const int size=3;   //variably modified 'board' at file scope

int board[size][size]; //init 3*3 array
int i=0,j=0;//i:row j:column
int  numofx,cx;
int numofo,co;
int result =-1;//tag:no one win

int main(){

//input the array
printf("please input your board:\n");
for(i=0;i<size;i++){
	for(j=0;j<size;j++){
		scanf("%d",&board[i][j]);
	}
}
printf("your board is :");
for(i=0;i<size;i++){
	printf("\n");
	for(j=0;j<size;j++){
		printf("%d\t",board[i][j]);
	}
}
//check the winner on row and column
//00 01 02
//10  11  12
//20 21 22
for(i=0;i<size && result==-1;i++){//result !=-1 no one win
	numofx=numofo=cx=co=0;//number of 0,1 is 0
	for(j=0;j<size;j++){
		if(board[i][j]==0) numofo++;//round1: 00 01 02
		else if(board[i][j]==1)numofx++;
		if(board[j][i]==0)co++;//round1:00 10 20
		else if(board[j][i]==1)cx++;
		//test
		//printf("\ni=%d j=%d\nfo=%d",i,j,numofo);
		//printf(" co=%d",co);
	}//for2
	if(numofx==size||cx==size) result=1;
	else if(numofo==size||co==size) result =0;
}//for1

//check the winner on diagonal
//00 01 02
//10 11 12
//20 21 22

// state 1
numofx=numofo=cx=co=0;//init the value
for(i=0;i<size && result==-1;i++){
	//00 11 22
	//i=j
	//only have three possible value,it's not necessary to check the result (-1)
	if(board[i][i]==1)cx++;
	else if (board[i][i]==0)co++;
}
if(cx==size) result=1;
else if(co==size) result =0;

//state 2
numofx=numofo=cx=co=0;//init the value
for(i=0;i<size && result==-1;i++){
	//02 11 20
	//i+j=size-1
	// i and j have the math connect ,use i to express j,just one "for" cycle
	if(board[i][size-1-i]==0)co++;
	else if (board[i][size-1-i]==1)cx++;
}
if(cx==size) result=1;
else if(co==size) result =0;

if(result!=-1)
	printf("\nthe winner is player %d",result);
else printf("\nno winner!");
}//main

please input your board:
1 0 1
0 1 0
1 0 0
your board is :
1       0       1
0       1       0
1       0       0
the winner is player 1

please input your board:
0 1 0
0 1 0
1 0 1
your board is :
0       1       0
0       1       0
1       0       1
no winner!

specially

please input your board:
1 1 0
1 1 0
1 1 0
your board is :
1       1       0
1       1       0
1       1       0
the winner is player 1

同时满足胜利条件但result为1
因为先执行行列判断

判断顺序如下:
R&C
1.0R 2.0C(First meet condition,result =1)
3.1R 4.1C
5.2R 6.2C

diagonal
7.00 11 22
8.02 11 20

back

C_190418_array

C_190418_array

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