英文:
Why does this piece of code say variable j might not have been initialized?? It is getting initialized inside the loop
问题
class Searching {
static int search(int arr[], int N, int X) {
int j;
for (int i = 0; i < N; i++) {
if (arr[i] == X) {
j = i;
break;
}
}
return j;
}
}
我在循环内部初始化了 j。所以为什么编译器在达到返回语句时会报告 j 未初始化。我作为一个编程新手无法理解。请帮助我。
英文:
class Searching{
static int search(int arr[], int N, int X)
{
int j;
for(int i = 0; i<N; i++){
if(arr[i] == X){
j = i;
break;
}
}
return j;
}
}
I have initialized j inside the loop. So why does the compiler say j is not initialized when it reaches the return statement. I am not able to understand as I am new to coding.. Please help me
答案1
得分: 1
在Java中，for循环是前测试循环：测试条件（i<N）在循环体之前执行。因此，如果N小于或等于i的初始值（0），循环将永远不会执行，且j将永远不会被初始化。
但还有另一个评论者忽略的问题：即使循环执行，如果要搜索的元素不存在于数组中，j也永远不会被初始化。
另外，与其将N作为参数传递，你应该能够直接从数组中获取它（虽然我现在无法记起如何做到这一点）。
英文:
In Java, for loops are pre-test loops: the test (i<N) is executed before the loop body. So if N is less than or equal to the initial value of i (0), then the loop wil never execute and j will never be initialised.
But there’s another issue that the commentators missed: even if the loop executes, if the element being searched for does not exist in the array, j will never be initialised.
On another note, instead of passing N as a parameter, you should be able to get it directly from the array (though I can’t remember how to do it right now).
答案2
得分: 1
这是因为参数 N 可能等于 0，所以循环不一定会执行，或者数组不包含 x，因此变量 j 不会被初始化。
我建议你像这样初始化：int j = -1;，然后如果方法返回 -1，你就会知道出了问题（N = 0 或数组不包含 x）。
英文:
This is happens because the parameter N can be equals to 0, so the loop isn't must running, or array isn't contains x, so the variable j will not initialize.
I suggest you to initialize like int j = -1;, and than if the method returns -1 you will know that something go wrong (N = 0 or array isn't contains x).
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