c - 基于 C 中用户输入的动态增长数组

Question

我需要创建一个程序:

1. initially allocate an array to read in and hold up to 5 temperatures.
2. prompt the user to enter temperatures and type the value -100.0 when they are finished
3. if the user fills up the array your program should dynamically allocate a new array which is double the size.
4. copy the old values across to the new array. deallocate the old array.
5. continue reading into the new array.
6. print the new array out when it's done

我是 C 语言的新手，有点卡住了。我知道如何创建一个动态数组，但我不知道如何创建一个新数组，一旦旧数组填满，它就会不断增长。

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

int main(void){
    int i,k; //loop count
    int j = 5; //initial array size
    int* temp = malloc(sizeof(int)*j); 
    int* newtemp;

    for (i = 0; i < j; i++){ //loop to read in temperature
        printf("enter temperature: ");
        scanf("%d",(temp+i));
        if (i=j){
        j = j*2; //double the size of initial array
        int* newtemp = malloc(sizeof(int)*j);
        strcpy(*newtemp,temp); // copy string
        for (k = 0; k < j; k++){ //loop to read in temperature
            printf("enter temperature: ");
            scanf("%d",(temp+i+k));
            }
        }
        switch (temp[i]){
            case (-100):
            temp[i] = '\0';
            i = 5; //loop ends
            break;
        }    
    }
    return 0;
}

错误信息:

tempp.c:18:16: warning: passing argument 1 of ‘strcpy’ makes pointer from integer without a cast [-Wint-conversion]
         strcpy(*newtemp,temp);
                ^
In file included from tempp.c:3:0:
/usr/include/string.h:121:14: note: expected ‘char * restrict’ but argument is of type ‘int’
 extern char *strcpy (char *__restrict __dest, const char *__restrict __src)
              ^~~~~~
tempp.c:18:25: warning: passing argument 2 of ‘strcpy’ from incompatible pointer type [-Wincompatible-pointer-types]
         strcpy(*newtemp,temp);
                         ^~~~
In file included from tempp.c:3:0:
/usr/include/string.h:121:14: note: expected ‘const char * restrict’ but argument is of type ‘int *’
 extern char *strcpy (char *__restrict __dest, const char *__restrict __src)

我知道我的代码很乱，而且我真的不知道在新数组不断增长时重新分配它的正确方法。请在这件事上给予我帮助。谢谢!

Answer 1

改用 realloc 工具如何？

void printArray(double *array, int size){
    for(int i=0; i<size; i++){
        printf("%.1lf ", array[i]);
    }
    putchar('\n');
}

int main(void){
    int size = 5;
    double *array = malloc(size * sizeof(double)); 
    double temperature;
    int i = 0;

    while(1){
        if(temperature == -100.0)
            break;
        if(i == size){
            size *= 2;
            array = realloc(array, size * sizeof(double));
        }
        scanf("%lf", &temperature);
        array[i] = temperature;
        printArray(array, size);
        i++;
    }
    free(array);
    return 0;
}