根据文件中的行创建数组

Question

首先，我不经常在这里发帖。如果这是不恰当的，我们深表歉意。我管理一些论坛，所以我理解为什么如果这是在错误的地方或回答了 1000 次(看上去成功率为 0。但可能没有看到正确的东西)，您会感到沮丧。

我正在为我的一个学位模块 (C) 做一项作业，但我被困在一个项目上。

我正在尝试创建一个接受输入(test.txt)的线性回归公式。读取文本文件，将文本文件放入 2 个单独的数组(xArray、yArray)中。

然后，程序获取这两个数组并使用它们来完成程序的其余部分(执行各种计算以产生最终结果)。

现在，程序按预期运行。我确实有一些缩进问题(很抱歉，如果它让你的眼睛流血)。我使用了一个测试文件(有 6 行)，它给出了正确的结果，所以如果它有效，我很高兴。

但是，只有当我使用与文件中的行匹配的数组大小时，它才有效(例如，如果文件中有 6 行，并且我将数组大小更改为 7)。它将产生 6 行精确值，第 7 行将为 0,0。这些值被视为 1,1。

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

int xArray[6];
int yArray[6];
int nValue = sizeof(xArray)/sizeof(int);
int totalX = 0;
int totalY = 0;
int totalXY = 0;
int totalXSquared = 0;
char ch;
char name[10];

void main() {

    // PROGRAM RUN
    arraySetting();
    sumofX();
    sumofY();
    sumofXY();
    sumofXSquared();
    formula();

}

int arraySetting() {

    int x, y, n;

    FILE *fptr;
    fptr = fopen("test.txt", "r");

    while (!feof(fptr)) {
        for (int a = 0; a <= 6; a++) {
            n = fscanf(fptr, "%d,%d", &xArray[a], &yArray[a]);
        }

    }

    fclose(fptr);

    printf("Read Data Printout\n");

    // ARRAY PRINT
    for (int a = 0; a < (sizeof(yArray)/sizeof(int)); a++) {
        printf("x = %d  y = %d\n", xArray[a], yArray[a]);
    }

    printf("\n");
    printf("Printout read complete\n");
    printf("Press ENTER key to Continue\n");    
    //here also if you press any other key will wait till pressing ENTER
    scanf("%c",&ch); //works as getchar() but here extra variable is required.    
}

int sumofX(){
    for (int a = 0; a < (sizeof(xArray)/sizeof(int)); a++) {
    totalX = totalX + xArray[a];

    }
    printf("The Sum of X is:%d\n",totalX);
    printf("Press ENTER key to Continue\n");    
    //here also if you press any other key will wait till pressing ENTER
    scanf("%c",&ch); //works as getchar() but here extra variable is required.    
}
int sumofY(){
        for (int a = 0; a < (sizeof(yArray)/sizeof(int)); a++) {
        totalY = totalY + yArray[a];
    }
    printf("The Sum of Y is:%d\n",totalY);
    printf("Press ENTER key to Continue\n");    
    //here also if you press any other key will wait till pressing ENTER
    scanf("%c",&ch); //works as getchar() but here extra variable is required.    
}
int sumofXY(){
        for (int a = 0; a < nValue; a++) {
        totalXY = totalXY + (xArray[a] * yArray[a]);
    }
    printf("The Sum of XY is:%d\n",totalXY);
    printf("Press ENTER key to Continue\n");    
    //here also if you press any other key will wait till pressing ENTER
    scanf("%c",&ch); //works as getchar() but here extra variable is required.    
}
int sumofXSquared(){
    for (int a = 0; a < (sizeof(xArray)/sizeof(int)); a++) {
        totalXSquared = totalXSquared + (xArray[a]*xArray[a]);
    }
    printf("The Sum of Xsquared is:%d\n",totalXSquared);
    printf("Press ENTER key to Continue\n");    
    //here also if you press any other key will wait till pressing ENTER
    scanf("%c",&ch); //works as getchar() but here extra variable is required.    
}

int formula() {
    // INPUT THEM INTO FORMULA TO FIND A & B
    double a;
    double b;
    double x;
    double y;
    double value;

    // A CALCULATION
    a = ((totalY * totalXSquared) - (totalX * totalXY));
    a = a / ((nValue * totalXSquared) - (totalX * totalX));

    // B CALCULATION
    b = ((nValue * totalXY) - (totalX * totalY));
    b = b / ((nValue * totalXSquared) - (totalX * totalX));

    // USER INPUT
    printf("Linear Regression formula\n\n");
    printf("Y = %.2lf + %.2lfx\n\n",a, b);
    printf("\nEnter a Value for X: ");
    scanf("%lf", &x);

    // USER INPUTTED VALUE INTO FORMULA TO CALCULATE 'Y'
    y = a + (b * x);
    printf("\nY = %.2lf + %.2lf x %.2lf\n", a, b, x);
    printf("Y = %.2lf\n", y);

}

如果使用上述，读取文件的输出如下:

x = 43  y = 99
x = 21  y = 65
x = 25  y = 79
x = 42  y = 75
x = 57  y = 87
x = 59  y = 81

Printout read complete
Press ENTER key to Continue

但是，如果 xArray 或 yArray 更改为不同的值(例如 7)。可以看到如下:

Read Data Printout
x = 43  y = 99
x = 21  y = 65
x = 25  y = 79
x = 42  y = 75
x = 57  y = 87
x = 59  y = 81
x = 0   y = 0

Printout read complete
Press ENTER key to Continue

我理解我正在尝试做的事情的概念。该数组需要灵活地处理文件中的行。但是，我不确定如何执行此操作。

如有任何帮助，我们将不胜感激。

Answer 1

指针int *xArray可用于根据需要分配内存。
realloc 用于更改内存分配。如果指针设置为 NULL，则第一次调用 realloc 的行为与调用 malloc 的行为相同。对于大文件，最好按 block 分配内存并跟踪内存使用情况，而不是为每对数字分配内存。

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

int *xArray = NULL;
int *yArray = NULL;
int nValue = 0;
int totalX = 0;

void arraySetting ( );
void sumofX ( );

int main ( void) {

    arraySetting ( );
    sumofX ( );

    free ( xArray);
    free ( yArray);

}

void arraySetting ( ) {
    int x, y;
    int *temp = NULL;
    FILE *fptr = NULL;

    if ( NULL == ( fptr = fopen("test.txt", "r"))) {
        perror ( "test.txt");
        exit ( EXIT_FAILURE);
    }

    while ( 2 == fscanf(fptr, "%d,%d", &x, &y)) {
        if ( NULL == ( temp = realloc ( xArray, sizeof ( *xArray) * ( nValue + 1)))) {
            fprintf ( stderr, "realloc problem xArray\n");
            exit ( EXIT_FAILURE);
        }
        xArray = temp;
        if ( NULL == ( temp = realloc ( yArray, sizeof ( *yArray) * ( nValue + 1)))) {
            fprintf ( stderr, "realloc problem yArray\n");
            exit ( EXIT_FAILURE);
        }
        yArray = temp;

        xArray[nValue] = x;
        yArray[nValue] = y;

        nValue++;
    }

    fclose(fptr);

    printf("Read Data Printout\n");

    // ARRAY PRINT
    for (int a = 0; a < nValue; a++) {
        printf("x = %d  y = %d\n", xArray[a], yArray[a]);
    }

    printf("\n");
    printf("Printout read complete\n");
    printf("Press ENTER key to Continue\n");
    //here also if you press any other key will wait till pressing ENTER
    char ch = 0;
    scanf("%c",&ch); //works as getchar() but here extra variable is required.
}

void sumofX ( ) {
    totalX = 0;
    for (int a = 0; a < nValue; a++) {
        totalX = totalX + xArray[a];
    }
    printf("The Sum of X is:%d\n",totalX);
    printf("Press ENTER key to Continue\n");
    //here also if you press any other key will wait till pressing ENTER
    char ch = 0;
    scanf("%c",&ch); //works as getchar() but here extra variable is required.
}