Python:
```python
def is_multiple_of_three(num):
if num % 3 == 0:
return True
else:
return False
测试
num = int(input("请输入一个数:"))
if is_multiple_of_three(num):
print(num, "是3的倍数")
else:
print(num, "不是3的倍数")
```
C语言:
```c
include
int main() {
int i = 0;
for (i = 1; i <= 100; i += 3) {
printf("%d ", i);
}
return 0;
}
```
C++:
```cpp
include using namespace std; int main() { int n = 1; while (n <= 50) { if (n % 3 == 0 || to_string(n).find('3') != -1) { cout<< n << endl; } n++; } return 0; } ``` C语言: ```c include int main() { int count = 0; for (int i = 1; i <= 100; i++) { if (i % 3 == 0) { printf("%d ", i); count++; if (count % 5 == 0) { printf("\n"); } } } return 0; } ``` C语言: ```c include int main() { int a, n; printf("请输入一个值 "); scanf("%d", &n); a = n - (n / 3) * 3; if (a == 0) { printf("您输入的数字是3的倍数 "); } else { printf("您输入的数字不是3的倍数 "); } return 0; } ``` 这些示例代码分别使用Python、C语言和C++编写，用于判断一个数是否是3的倍数或打印1到100之间的所有3的倍数。你可以根据需要选择合适的编程语言和代码示例。