[英]Random lottery number generator in C programming
I want to do generate 7 different number (0-9) - first digit should not be 0- and put them into an array.我想生成 7 个不同的数字 (0-9) - 第一个数字不应该是 0- 并将它们放入一个数组中。 Every number should be unique.每个数字都应该是唯一的。 I know what I did wrong but I dont know what should I do.我知道我做错了什么,但我不知道我该怎么做。
int arr[7], j, i;
srand(time(NULL));
for (i = 0; i < 7; i++)
{
arr[i] = rand() % 10;
if (arr[0] == 0)
arr[0] = rand() % 10;
}
for (i = 0; i < 7; i++)
{
for (j = 0; j < 7; j++)
{
if (i == j) {
j++;
}
if (arr[i] == arr[j])
arr[j] = rand() % 10;
}
}
printf("\n");
for(j=0;j<7;j++)
printf("\n%d ", arr[j]);
rand() % 9 + 1
to produce random number between 1 and 9.您可以使用rand() % 9 + 1
生成 1 到 9 之间的随机数。arr[j]
may be out-of-range after j++;
arr[j]
在j++;
. .Try this:尝试这个:
int arr[7], j, i;
srand(time(NULL));
arr[0] = rand() % 9 + 1; /* decide first number with special formula */
for (i = 1; i < 7; i++) /* decide the rest numbers */
{
int dupe = 0;
arr[i] = rand() % 10;
for (j = 0; j < i; j++) /* check against numbers that already decided */
{
if (arr[i] == arr[j])
dupe = 1; /* ouch, this number is already used! */
}
if (dupe)
i--; /* if the number is already used, try again */
}
printf("\n");
for(j=0;j<7;j++)
printf("\n%d ", arr[j]);
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