Question

我在C程序中收到一个文件作为参数

每行具有不同的整数，如下所示：

1 2 4 5 6
7 8 8 9 10 -1 2 3
12 3 4 -2 2 -3 9 2 4

我想将每行的前2个参数设置为一个int值，并将其余所有参数设置为类似数组的第2行：

int a;
int b;
int c[10];

int a = 7;
int b = 8;
int c = [8,9,10,-1,1,2,3]

我能够获得前2个，但无法在数组中实现它。

任何帮助将不胜感激

这就是我现在拥有的：

//get line per line until \n
while (fscanf(fp, "%d %d", a, b) != EOF)
    while (fscanf(fp,"%d [^\n]", c[n]) != EOF)
        n++;

// print each line
for ( int k = 0 ; k < 10; k ++)
    printf("%d %d %d \n", a, b, c[k]);

Answer 1

仅使用fscanf分隔行可能很棘手。最好使用fgets读一行，然后使用sscanf从那里读数字。

此外，fscanf和sscanf返回匹配的项目数。您不应该检查EOF。

char line[300];
while (fgets(line, sizeof(line), fp)) {
    int rval = sscanf(line, "%d %d", &a, &b);
    if (rval == 2) {
        int count = 0;
        do {
            rval = sscanf(line, "%d", &c[count++]);
        } while (rval == 1);
    } 
}

Answer 2

阅读C read file line by line和How to extract numbers from string in c?，然后您将得到如下内容：

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

int main(void) {
    FILE * fp;
    char * line = NULL;
    size_t len = 0;
    ssize_t read;

    fp = fopen("input.txt", "r");
    if (fp == NULL)
        return -1;

    while ((read = getline(&line, &len, fp)) != -1) {
        printf("Retrieved line of length %zu:\n", read);
        //printf("%s", line);
        char* p = line;
    int a, b, c[10], counter = -2;
    while (*p) { // While there are more characters to process...
            if ( isdigit(*p) || ( (*p=='-'||*p=='+') && isdigit(*(p+1)) )) {
                // Found a number
                long val = strtol(p, &p, 10); // Read number
                //printf("%ld\n", val); // and print it.
            if(counter == -2)
                a = val;
            else if(counter == -1)
                b = val;
            else if(counter < 10)
                c[counter] = val;
            counter++;
            } else {
                // Otherwise, move on to the next character.
                p++;
            }
    }
    printf("a = %d, b = %d\n", a, b);
    for(int i = 0; i < counter; ++i)
        printf("%d ", c[i]);
    printf("\n");
    }

    fclose(fp);
    if (line)
        free(line);
    return 0;
}

输出：

Retrieved line of length 10:
a = 1, b = 2
4 5 6 
Retrieved line of length 18:
a = 7, b = 8
8 9 10 -1 2 3 
Retrieved line of length 21:
a = 12, b = 3
4 -2 2 -3 9 2 4

fscanf转换为int和array

2 个答案: