这个代码哪里错了请问

16行改为
printf("%.2f",250+a-300);

逻辑混乱
if (a > 300) if (250 + a - 300 > 400)
这里，前一个条件不需要，后面的条件，a > 450 即可（因为>450天然就大于300了）

printf("%.2f", b=0.8a)
这里，到底是输出b还是让bi=0.8a，分开写。如果b只用到一次，这个b本身就是多余的

printf(250+a-300);
这里，你要输出什么，如果输出值，应该是printf("%.2f",250+a-300);

不知道你这个问题是否已经解决, 如果还没有解决的话:

• 这篇文章讲的很详细，请看：企业的代码发布解决方案
• 除此之外, 这篇博客: 单链表完整代码中的 单链表 部分也许能够解决你的问题, 你可以仔细阅读以下内容或者直接跳转源博客中阅读:
  

  #include <stdio.h>
  #include <stdlib.h>
  
  typedef struct Node{
      int data;
      struct Node *next;
  }Node, *LinkedList;
   
  Node insert(LinkedList head, Node *node, int index) {
      Node *p, ret;
      p = &ret;
      ret.data = 0;
      ret.next = head;
      while (p->next && index) {
          p = p->next;
          --index;
      }
      if (index == 0) {
          node->next = p->next;
          p->next = node;
          ret.data = 1;
      }
      return ret;
  }
  void output(LinkedList head) {
      Node *p = head;
      while (p) {
          printf("%d", p->data);
          if (p->next) {
              printf(" ");
          }
          p = p->next;
      }
      printf("\n");
  }
  
  void clear(LinkedList head) {
      Node *p, *q;
      p = head;
      while (p) {
          q = p->next;
          free(p);
          p = q;
      }
      return ;
  }
  
  int main() {
      LinkedList linkedlist = NULL;
      Node *p, ret;
      int n, num, loc;
      scanf("%d", &n);
      for (int i = 0; i < n; ++i) {
          scanf("%d%d", &loc, &num);
          p = (Node *)malloc(sizeof(Node));
          p->data = num;
          p->next = NULL;
          ret = insert(linkedlist, p, loc);
          linkedlist = ret.next;
          printf("%s\n", ret.data ? "success" : "failed");
      }
      output(linkedlist);
      clear(linkedlist);
      return 0;
  }
  

  #include <stdio.h>
  #include <stdlib.h>
  
  typedef struct Node{
      int data;
      struct Node *next;
  }Node, *LinkedList;
  
  LinkedList insert(LinkedList head, Node *node, int index) {
      if (head == NULL) {
          if (index != 0) {
              printf("failed\n");
              return head;
          }
          head = node;
          printf("success\n");
          return head;
      }
      if (index == 0) {
          node->next = head;
          head = node;
          printf("success\n");
          return head;
      }
      Node *current_node = head;
      int count = 0;
      while (current_node->next != NULL && count < index - 1) {
          current_node = current_node->next;
          count++;
      }
      if (count == index - 1) {
          node->next = current_node->next;
          current_node->next = node;
          printf("success\n");
          return head;
      }
      printf("failed\n");
      return head;
  }
  
  void output(LinkedList head) {
      if (head == NULL) {
          return;
      }
      Node *current_node = head;
      while (current_node != NULL) {
          printf("%d ", current_node->data);
          current_node = current_node->next;
      }
      printf("\n");
  }
  
  Node delete_node(LinkedList head, int index) {
      Node ret, *p, *q;
      ret.data = 0;
      ret.next = head;
      p = &ret;
      while(p->next && index) {
          p = p->next;
          --index;
      }
      if(p->next) {
          q = p->next;
          p->next = q->next;
          free(q);
          ret.data = 1;
      }
      return ret;
  }
  
  LinkedList reverse(LinkedList head) {
      Node ret;
      ret.next = NULL;
      Node *p, *q;
      p = head;
      while(p) {
          q = p->next;
          p->next = ret.next;
          ret.next = p;
          p = q;
      }
      return ret.next;
  }
  
  void clear(LinkedList head) {
      Node *current_node = head;
      while (current_node != NULL) {
          Node *delete_node = current_node;
          current_node = current_node->next;
          free(delete_node);
      }
  }
  
  int main() {
      LinkedList linkedlist = NULL;
      int n;
      Node ret;
      scanf("%d", &n);
      while(n --) {
          int w;
          scanf("%d", &w);
          if(w == 1) {
              int a, b;
              scanf("%d%d", &a, &b);
              Node *node = (Node *)malloc(sizeof(Node));
              node->data = b;
              node->next = NULL;
              linkedlist = insert(linkedlist, node, a);
          }
          if(w == 2) {
              output(linkedlist);
          }
          if(w == 3) {
              int a;
              scanf("%d", &a);
              ret = delete_node(linkedlist, a);
              linkedlist = ret.next;
              printf("%s\n", ret.data ? "success" : "failed");
          }
          if(w == 4) {
              linkedlist = reverse(linkedlist);
          }    
      }
      clear(linkedlist);
      return 0;
  }
  

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