無法解決無限循環

該程序應該採取一個用戶輸入的整數，並通過單向鏈接列表將其轉換爲二進制。我認爲它是我的toBin（）函數或我的printStack（）函數導致的無限循環。無法解決無限循環

#include <stdio.h> 
#include <stdlib.h> 
#include <math.h> 

typedef struct node_def node; 

struct node_def 
{ 
    int val; 
    node *next; 
}; 

node *head; 

void push(int val); 
void pop(node *head); 
int top(); 
void printStack(); 
int toBin(int val); 

int main() 
{ 
    int num = 0; 

    printf("Enter an integer: "); 
    scanf("%d", &num); 
    push(num); 
    toBin(num); 
    printStack(); 

    return 0; 

} 

void push(int val) 
{ 
    node *new; 
    new = malloc(sizeof(node)); 

    if (head == NULL) 
    { 
     head = malloc(sizeof(node)); 
     head->next = NULL; 
     head->val = val; 
    } 
    else 
    { 
     new->next = head; 
     new->val = val; 
     head = new; 

    } 

    return; 
} 

void pop(node *head) 
{ 
    node *tmp; 
    if(head == NULL) 
    { 
     printf("Stack is Empty\n"); 
     return; 
    } 
    else 
    { 
     tmp = head; 
     head = head->next; 
     free(tmp); 
    } 
    return; 
} 

int top() 
{ 
    return(head->val); 
} 

void printStack() 
{ 
    node *tmp; 
    tmp = head; 

    if(head == NULL) 
    { 
     return; 
    } 

    while(head != NULL) 
    { 
     printf("%d ", head->val); 
     head = head->next; 
    } 
    printf("\n"); 
    return; 
} 

int toBin(int val) 
{ 
    pop(head); 
    int i = 1, remainder, binary; 

    while(val != 0) 
    { 
     remainder = val % 2; 
     binary = binary + remainder * i; 
     val = val/2; 
     i = i * 10; 
     push(binary); 
    } 

    return val; 
}

來源

2017-04-26 mychem97

在'printStack（）'定義'tmp'但不使用它。相反，你修改全局'head'，從此'head'就沒用了。 –

@WeatherVane我也在我的pop（）函數中做了這個。改變了兩者之後，無限循環消失了，謝謝！ – mychem97

但是，在'pop（node * head）'中可以，因爲你正在修改一個傳值參數，而不是被'printStack（）修改的全局變量' – bruceg

由於未正確初始化變量，您將陷入無限循環。特別是，你不能保證你的node *頭部將被初始化爲NULL，或者你的toBin（）中的int變量將被初始化爲零。

始終，總是，總是在C/C++編程時初始化您的變量。

修復這些錯誤，並刪除未使用的代碼給我們留下了：

#include <stdio.h> 
#include <stdlib.h> 

typedef struct node_def node; 

struct node_def 
{ 
    int val; 
    node *next; 
}; 

/* Note that we are initialising the global variable to NULL. */ 
node *head = NULL; 

void push(int val); 
void printStack(); 
int toBin(int val); 

int main() 
{ 
    int num = 0; 

    printf("Enter an integer: "); 
    scanf("%d", &num); 

    /* Removed push(num), as you're using parameters in the following call: */ 
    toBin(num); 
    printStack(); 

    return 0; 

} 

/* Changed printStack to use a tmp pointer to 
    traverse the stack without mutating it */ 
void printStack() 
{ 
    node* tmp = head; 
    while(tmp != NULL) 
    { 
     printf("%d ", tmp->val); 
     tmp = tmp->next; 
    } 
    printf("\n"); 
    return; 
} 

int toBin(int val) 
{ 
    /* Removed pop() as you're getting val from parameters */ 

    /* Also initialising remainder and binary variables */ 
    int i = 1, remainder = 0, binary = 0; 

    while(val != 0) 
    { 
     remainder = val % 2; 
     binary = binary + remainder * i; 
     val = val/2; 
     i = i * 10; 
     push(binary); 
    } 

    return val; 
} 

/* It's a stack so no if's are necessary for pushing */ 
void push(int val) 
{ 
    node *new = malloc(sizeof(node)); 
    new->val = val; 
    new->next = head; 

    head = new; 
    return; 
}

來源

2017-04-26 22:39:57 sigbjornlo

無法解決無限循環

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