C 从文本文件中读取数字

Question

我正在尝试从 txt 文件中获取数字，我编写了如下代码；

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

int main() {
    FILE *file;
    file = fopen("example_input.txt", "r");
    fseek(file, 0L, SEEK_END);   
    long int res = ftell(file);
    fseek(file, 0L, SEEK_SET);
    int n[9999];

    for (int i = 0; i < res; i++) {   
        fscanf(file, "%d,", &n[i]);
    }
    int size = sizeof(n)/ sizeof(n[0]);
    for (int a = 0; a < size + 1; a++) {
        printf("%d ", n[a]);
    }
}

它工作正常，但我想创建更多动态数组，txt 文件在每个数字之间有一个逗号，所以我添加了一段计算逗号的代码，并试图找到 txt 文件中的数字数量。我做了这样的代码

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

int main() {
    FILE *file;
    file = fopen("example_input.txt","r");
    fseek(file, 0L, SEEK_END);   
    long int res = ftell(file);
    fseek(file, 0L, SEEK_SET);
    int m;
    int counter = 0;
    while((m = fgetc(file)) != EOF) {
        if (m == 44) {
            counter += 1;
        }
    }
    int n[counter];

    for (int i = 0; i < res; i++) {   
        fscanf(file, "%d,", &n[i]);
    }
    for (int a = 0; a < counter + 1; a++) {
        printf("%d ", n[a]);
    }
}

此更改后，程序开始随机生成输出。这是什么原因？

第一段代码的部分输出如下所示：

46 92 31 66 55 82 11 95 68 13 62 18 16 43 12 22 82 10 45 90 55 84 6 27 2 47 67 51 20 42 51 36 3 87 74 18 46 21 45 87 22 47 17 32 68 48 34 76 56 22 43 64 22 43 96 74 7 58 96 16 71 23 32 85 70 70 56 56 85 52 14 85 80 57 1 12 34 54 80 37 49 53 39 85 55 15 75 76 98 37 8 28 20 67 92 67 43 48 63 54 17 88 53 76 12 29 94 22 49 61 22 96 62 33 86 38 94 63 79 21 45 46 43 25 22 38 33 93 2 19 10 25 9 36 34 57 95 25 12 42 90 10 32 38 15 39 83 53 24 24 80 39 5 62 53 17 39 77 68 47 70 85 41 5 98 68 99 23 38 2 36 0 11 3 89 54 53 35 17 19 81 92 13 87 62 49 58 2 15 7 8 63 37 19 65 38 31 40 22 11 99 43 24 52 83 18 54 77 85 36 30 52 72 22 19 71 97 74 87 23 50 92 7 66 21 1 8 69 9 49 55 53 91 70 18 2 20 59 38 19 6 55 9 77 17 54 1 79 15 51 83 27 93 16 78 75 67 11 28 52 27 38 96 52 34 65 29 50 30 52 94 99 51 16 83 48 69 80 89 6 31 66 50 8 44 4 40 51 32 92 88 16 53 23 63 48 75 65 29 1 57 23 38 9 56 7 54 74 39 33 20 81 48 28 24 89 45 19 7 1 18 21 28 26 76 96 68 74 72 78 66 37 86 15 49 34

第二个像这样：

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0 713594160 32767 -458707629 32653 0 0 155648 0 151736 0 151736 0 0 0 1 0 155648 0 1503232 0 1502284 0 1502284 0 155648 0 5 0 1503232 0 1810432 0 1808899 0 1808899 0 1503232 0 1 0 1814528 0 1839104 0 1836592 0 1852480 0 1810432 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1194 0 8192 0 -458634272 32653 0 0 0 0 -458838016 32653 -458694208 32653 0 0 -458559904 32653 32 0 -458836864 32653 10 0 0 0 0 0 0 0 713594160 32767 -458694993 32653 0 0 713594160 32767 -458838016 32653 -458707945 32653 0 0 0 0 0 3 -458841024 32653 3 4095 713593824 32767 3 0 1852480 0 0 0 713594376 32767 6 0 -458854400 32653 1017627840 22008 -458559904 32653 0 3 -458563360 32653 2049 0 399077 0 2049 0 399077 0 1 0 33261 0 0 0 0 0 1839168 0 4096 0 3600 0 1636126187 0 400000112 0 1632077219 0 0 0 1636037385 0 769124878 0 0 0 0 0 0 0 -458756030 32653 0 0 -458563104 32653 -458673324 32653 -458567616 32653 0 0 0 0 -458705939 32653 1 0 0 0 713594296 32767 0 0 1 0 0 0 -458559904 32653 0 0 -4585

Answer 1

您需要在计算所有逗号后查找到文件的开头。当你开始 fscanf() 循环时，你在文件的末尾，所以它们都失败了，你没有阅读任何东西。

读取数字的循环应该只有运行 counter 次。 res是文件的字节数，至少是数字的两倍。使用 res.

没有意义

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

int main() {
    FILE *file;
    file = fopen("example_input.txt","r");
    int m;
    int counter = 0;
    while((m = fgetc(file)) != EOF) {
        if (m == ',') {
            counter++;
        }
    }
    counter++; // 1 more for the last number
    int n[counter] = {0};

    fseek(file, 0L, SEEK_SET);

    for (int i = 0; i < counter; i++) {   
        if (fscanf(file, "%d,", &n[i]) != 1) {
            break;
        }
    }
    for (int a = 0; a < counter; a++) {
        printf("%d ", n[a]);
    }
}

C 从文本文件中读取数字

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