如何从C中的.txt文件读取数字 [英] How to read numbers from a .txt file in C

问题描述

如何做到这一点，使程序仅从.txt文件中读取字符串中的数字?这样一来，您就可以存储它们并将其用于以后的转换.

How can you make it so the program reads only the numbers in a string from a .txt file? This is so you can then store them and use them for later transformations.

我想我只知道数字是怎么做的，就像您的文件中包含"0.3 0.4"一样:

I think I know how to do it if it were numbers only, like if you had a file that had "0.3 0.4":

fscanf(fp, "%f %f\n", &x, &y);

或者如果它是在每一行中始终相同的字符串.例如，在一个文件中，有几行像这样:"sin(0.348889)= 0.341854".然后，要读取数字，您只需要执行以下操作即可:

Or if it were a string that was always the same in each line. Example, in a file, there's several lines like this one: "sin(0.348889)=0.341854". Then to read the numbers you'd only have to do something like this:

fscanf(fp, "sin(%f)=%f\n", &x, &y);

但是，当字符串并不总是相同时，您将如何做呢?如何从该文件中读取某些数字?我知道要问的问题太多了，但是读书对我没有帮助，我已经尝试过在互联网上搜索，所以我决定投篮了.

But how do you do you do it when the strings are not always the same? How to read certain numbers from that file? I know this is way too much to ask, but reading the book isn't helping me and I already tried searching in the internet, so I decided to take the shot..

推荐答案

通过读取字符，可以不从字符串中跳过数字.像这样:

You can skip not numbers from string by reading chars. Something like this:

int n;
float number;
errno = 0;
while (!errno) {
    n = fscanf(fp, "%f", &number);
    if (n == 1) {
        /* do something with number */
    } else {
        char c;
        n = fscanf(fp, "%c", &c);
        if (n != 1) { /* EOF */
            break;
        }
    }
}

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