C言語で配列を定義するにはどうすればよいですか?

int a[5];
char c[3];

int a[5] = {1, 2, 3, 4, 5};
int arr[] = {1,2,4};
int arr[10] = {1,2};

char str1[5]=“hello”;   //定义数组长度：30
char str1[30] = { 'L', 'e', 't', '\'', 's',' ', 'g', 'o', '\0' };  // 字符串长度：8；数组长度：30
char str1[30] = "Let's go";   // 字符串长度：8；数组长度：30
char str2[] = " to London!";    // 字符串长度：11 （注意开头的空格）；数组长度：12

int a[3][4];
char c[3][10];

int a[1][3]={};
int a[][4]={1,2,3,4,5,6,7,8,9,10,11,12};
int a[][4]={{0,0,3},{},{}0,10}};

char c[5][5]={{'a','s','d',},{'a','s','d','c'},{'a','s','d','c','f'},{'s','d','c','f'},{'d','c','f'}}；
char c[5][5]={"hgbv","jhg","jhgf","iuh","jjhs"};
char c[][5]={"ssdf","adfv"};