c - 如何根据c中的位置打印字符串？

Question

我正在解决一个问题，需要我在该位置打印给定字段编号的字符串。应从文件中读取字符串。

文件.txt

C is a language.
lex lexical analyser
(blank line)
      gcc is good

如果field-number是2(即句子中的第二个单词)。程序应该输出

is
lexical
(NULL)
is

我编写了一个函数，但不认为它是正确的方法并且它适用于所有情况。它应该处理额外的空格或换行符。

while (fgets(buffer, MAX, file) != NULL) {
    for (int i = 1; i < strlen(buffer); i++) {
        if (count == field_number - 1) {
            int j = i;
            while (j < strlen(buffer) && buffer[j] != ' ') {
                printf("%c", buffer[j++]);
            }
            printf("\n");
            count = 0;
            break;
        }

        if (buffer[i] == ' ' && buffer[i - 1] != ' ') {
            count++;
        }
    }
}

我是初学者。这段代码应该很容易理解。

Answer 1

这应该适用于所有情况，

int main() {
    //FILE* file = fopen(__FILE__, "r");
    //int field_number = 2;

    int new_line = 0; // var to keep track of new line came or not
    int word = 0;
    int count = 0;
    char c, prev_c;
    while ((c = fgetc(file)) != EOF) {
        // printf("[%c]", c);
        // if a new line char comes it means you entered a new line
        if(c == '\n') {
            // you have to print the new line here on the output to handle
            // empty line cases
            printf("\n");
            new_line = 1; // when line changes
            word = 0; // no word has come in this new line so far
            count = 0;    // count becomes 0
        } else if( c == ' ' && prev_c != ' ') {
            if(word)
                count++;
            if(count == field_number) // if count exceeds field_number
                new_line = 0; // wait till next line comes
        } else if (new_line && count == field_number - 1) {
            printf("%c", c);
        } else {
            word = 1; // fi a not new line or non space char comes, a word has come
        }
        prev_c = c;
    }
    return 0;
}