Question

所以我试着自学，并且我一直在做在线实验练习来学习它。我写了一个程序，它详细介绍了数组和结构。它使用随机数监视100 psi的峰值，然后将其打印为0点，并打印阵列的前10秒和下一个10秒，就好像我正在收集数据一样。本练习的下一部分是获取程序的print语句，并将其写入外部文件并将其打印在那里。我的思考过程是在打印输出函数中填充一个数组，该数组包含从文件中读取的值，然后从数组打印到屏幕。但我不确定这看起来如何，或者真的如何实现它。如果有人能指出我正确的方向或给出一个很好的解释，将不胜感激！

到目前为止我的代码：

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

#define MAX_CHANGE      100
#define ARRAY_SIZE      21

typedef struct data_slice
{
        int t;          // -> Time
        float tp;       // -> Valve pressure
    float tf;       // -> Sodium flow
    float tt;       // -> Sodium temp in Celsius
} data_slice;

// Function Declarations
void get_values(float * pressure, float * flow, float * temp);
void printIt(data_slice * data);
void initializeArray(data_slice * data);
bool spikeValueRecorded(data_slice * data, int outputIndex);


int main()
{
    srand((unsigned int)time(NULL));
    data_slice data[ARRAY_SIZE];
    int index = -1;

    while (1)
    {
        // Initialize the entire array
        initializeArray(data);

                    // If there's a spike.....
        if (spikeValueRecorded(data, index))
        {
            // Set the previous "time" in array to negatives
            int temp = index;
            for (int i = 0; i >= -10; --i)
            {
                data[temp].t = i;
                temp = temp - 1;
                if (temp < 0)
                    temp = temp + ARRAY_SIZE;
            }

                // Record for 10 more seconds
            for (int i = 0; i <= 10; ++i)
            {
                data[index].t = i;
                index = (index + 1) % ARRAY_SIZE; //         Increment the index of the circular array
                get_values(&data[index].tp, &data[index].tf,    &data[index].tt);       // "Record" the values
            }
            break;
        }
    }
    // Print the finished recording
    printIt(data);
}

// Return: void
// in - Values of the data_slice struct
//
// Description: The three values of the struct (data_slice) to be filled in
void get_values(float * pressure, float * flow, float * temp)
{
    *pressure   = (float)(rand() % (700 - 500 + 1) + 500);  //    Range: 500 - 700
    *flow       = (float)(rand() % (20 - 10 + 1) + 10);     //   Range: 10 - 20
    *temp       = (float)(rand() % (200 - 100 + 1) + 100);  //  Range: 100 - 200
}

// Return: void
// in - The array of data_slice
//
// Description: Prints the entire array being passed in
void printIt(data_slice * data)
{
    // Find the indice holding the time value of -10
     int indice = 0;
    for (int i = 0; i < ARRAY_SIZE; ++i)
    {
        if (data[i].t == -10)
        {
            indice = i;
            break;
        }
    }

    for (int i = 0; i < ARRAY_SIZE; ++i)
    {
        printf("%i\t %f\t %f\t %f\n", data[indice].t, data[indice].tp,    data[indice].tf, data[indice].tt);
        indice = (indice + 1) % ARRAY_SIZE;
    }
}

// Return: void
// in - The array of data_slice
//
// Description: Initializes the entire array to random values and their   times to 0
void initializeArray(data_slice * data)
{
    for (int i = 0; i < ARRAY_SIZE; ++i)
    {
        data[i].t = 0;
        get_values(&data[i].tp, &data[i].tf, &data[i].tt);
    }
}

// Return: boolean
// in - The array of data_slice
// out - Indice of the pressure spike
//
// Description: Returns true if a positive spike in pressure has been   recorded.
//      outputIndex will hold the 0-indice of the pressure spike, else -1
bool spikeValueRecorded(data_slice * data, int outputIndex)
{
    float oldValue = data[0].tp;
    for (int i = 0; i < ARRAY_SIZE; ++i)
    {
        if (data[i].tp - oldValue < MAX_CHANGE)
        {
            outputIndex = i;
            return true;
        }
    }
    outputIndex = -1;
    return false;
}

Answer 1

你可以像使用printf一样使用fprintf调用，但有一点不同。第一个参数将是一个指向文件句柄（FILE *）的指针，您可以使用对fopen的调用（“完整或相对路径”，“w”）创建它。

字符串格式现在是第二个参数，变量args列表从arg 3开始

Answer 2

这是您可以使用libc API

写入文件的方式

void printIt(data_slice * data)
{
    // Find the indice holding the time value of -10
     int indice = 0;
    for (int i = 0; i < ARRAY_SIZE; ++i)
    {
        if (data[i].t == -10)
        {
            indice = i;
            break;
        }
    }
     //write to file 
    FILE *fp = fopen("output.txt", "wb"); //Binary mode since the size of array is fixed.
    fwrite(data, sizeof(char), sizeof(data), fp);
    fclose(fp);

    for (int i = 0; i < ARRAY_SIZE; ++i)
    {
        printf("%i\t %f\t %f\t %f\n", data[indice].t, data[indice].tp,    data[indice].tf, data[indice].tt);
        indice = (indice + 1) % ARRAY_SIZE;
    }

}

将打印语句导出到外部文件

2 个答案: