C language programming> thirteenth week ② Please write the function fun, the function of this function is: to put M strings in the string array (the length of each string does not exceed N), merge them in order to form a new character string.

Example: Please write the function fun. The function of this function is to combine the M strings (the length of each string does not exceed N) in the string array into a new string in order.

例如，若字符串数组中的M个字符串为：
1 1 1 1
2 2 2 2 2 2 2
3 3
4 4 4 4
则合并后的字符串的内容应是11112222222334444
请勿改动主函数main与其它函数中的任何内容，仅在函数fun的花括号中填入所编写的若干语句。

代码如下：

#include<stdio.h>
#define M 4
#define N 20
void fun(char str[M][N],char*a)
{
    
    
	int i,j,k=0;
	for(i=0;i<M;i++)
	{
    
    
		for(j=0;j<N;j++)
			if(*(*(str+i)+j))
			{
    
    
				a[k]=*(*(str+i)+j);
				k++;
			}
		else
		break;
		a[k]='\0';
	}
}
main()
{
    
    
	char matrix[M][N]={
    
    "1111","2222222","33","4444"},i;
	char str[100]={
    
    "****************"};
	FILE*out;
	printf("The string:\n");
	for(i=0;i<M;i++)
		puts(matrix[i]);
	printf("\n");
	fun(matrix,str);
	printf("The string:\n");
	printf("%s",str);
	printf("\n\n");
	out=fopen("outfile.dat","w");
	fprintf(out,"%s",str);
	fclose(out);
}

The output running window is as follows:

越努力越幸运！
加油，奥力给！！！