c - AddNumber 函数问题

Question

我无法理解如何从程序中获取用户输入并将其传递到函数 AddNumber 中。该程序将启动并要求用户输入并将其存储到输入数组中，但我不确定如何从数组中获取信息并将其传递给函数AddNumber。

我已经更新了代码，据我了解，我的“AddNumber”函数没有执行任何操作。我的印象是我创建了指针“previous”，应该 previous = NULL 吗？

#include "stdio.h"
#include "string.h"
#include "stdlib.h"

typedef struct A_NewNumber {
  struct A_NewNumber *next;
  char newNum;
} NewNumber;

NewNumber *AddNumber(NewNumber *previous, char *input){

//char input[16];
//double numEntered = 0;

NewNumber *newNum = malloc(sizeof(NewNumber));
sscanf(input, "%lf", &newNum->newNum);

//sscanf(input, "%s", newNum->enterNumber);
//numEntered = atof(input);
//possible code 
/*if (previous != NULL){
    previous->newNum;
}
newNum->next = NULL;
newNum->newNum = 0;
return newNum;

}*/


void PrintList(NewNumber *numStart) {
  NewNumber *currentNumber = numStart;
  int count = 0;

  while (currentNumber != NULL) {
    count++;
    printf("Number Position:%s\n", currentNumber->enterNumber);
    currentNumber = currentNumber->next;
  }
  printf("Total Numbers Entered%d\n", count);
}

void CleanUp(NewNumber *start) {
  NewNumber *freeMe = start;
  NewNumber *holdMe = NULL;

  while (freeMe != NULL) {
    holdMe = freeMe->next;
    free(freeMe);
    freeMe = holdMe;
  }
}

int main(){

   //indexNum = 0;
   char command[16];
   char input[16];
   //float userInput;
   NewNumber *userEnter = NULL;
   NewNumber *start = NULL;
   NewNumber *newest = NULL;

   while(fgets(input, sizeof input, stdin)){
    printf("Please enter a number->");
    printf("Enter 'quit' to stop or 'print' to print/calculate");
    sscanf(input, "%s", command);
    if(newest == NULL){
        start = AddNumber(NULL, input);
        newest = start;
    }else{
        newest = AddNumber(newest, input);
    }
    if( strncmp(command, "print", 5) == 0){
        PrintList(start);
    }else if( strncmp(command, "quit", 4)== 0){
        printf("\n\nQuitting....\n");
        break;
        //userInput = enterNumber;
    }
  }
  CleanUp(start);
  return 0;
}

Answer 1

在不过多修改代码的情况下，我建议 AddNumber 采用指向前一个 NewNumber 的指针以及用户输入。您的意图似乎是也要读取 double ，因此我将 newNum 字段修改为 double 类型。像这样的事情:

typedef struct A_NewNumber{
    struct A_NewNumber *next;
    double newNum;
} NewNumber;

NewNumber *AddNumber(NewNumber *previous, char *input){

    NewNumber *newNum = malloc(sizeof(NewNumber));
    /* use %lf to read in a double */
    sscanf(input, "%lf", &newNum->newNum);

    if (previous != NULL){
        previous->next = newNum;
    }

    return newNum;
}

然后，当您调用 AddNumber 函数时，您可以传递前一个和输入，例如

if(newest == NULL){
    start = AddNumber(NULL, input);
    newest = start;
} else {
    newest = AddNumber(newest, input);
}