为什么FSCANF可以用来首先在C中读取c？

发布于 2025-02-07 21:10:06 字数 869 浏览 0 评论 0原文

我是C编程的新手。所以我也许有一个简单的问题。那么，为什么不能使用fscanf无法使用fopen（读取模式）？我的意思是，据我了解，我必须首先使用fopen（写模式），然后fopen（读取模式）将起作用。如果我先在fopen（写模式）之前首先使用fopen（读取模式），则该代码在此代码中的工作状态不佳。另一件事是，为什么fscanf无法在此代码中读取空间？我已经尝试了％*s，而Fopen（读取模式）首先不起作用。

这是我的简单代码：

int main() {
    FILE *fp;
    fp = fopen("Test.txt", "r+");
    char name[100], hobby[100];
    int age;
    fscanf(fp, "Name:%*s\nAge:%d\nHobby:%*s", &name, &age, &hobby);
    printf("\nScan Result\n%s\n%d\n%s", name, age, hobby);
    fclose(fp);
    return 0;
}

test.txt 文件：

Name:This is a test
Age:21
Hobby:Play games

当我运行它时：


Scan Result
`░
0
 >m
Process returned 0 (0x0)   execution time : 0.016 s
Press any key to continue.

我错过了什么吗？还是不可能？回答给出的代码对我学习更好，谢谢。

原文

I'm new to C programming. So I have maybe a simple question. So why fscanf with fopen(read mode) can't be used? I mean, from what I learned I must use fopen(write mode) first so then fopen(read mode) will work. If i use fopen(read mode) first before fopen(write mode) it wouldn't work like in this code. Another thing is, why fscanf can't read space in this code? I already tried %*s while fopen(read mode) first and it didn't work.

Here is my simple code:

int main() {
    FILE *fp;
    fp = fopen("Test.txt", "r+");
    char name[100], hobby[100];
    int age;
    fscanf(fp, "Name:%*s\nAge:%d\nHobby:%*s", &name, &age, &hobby);
    printf("\nScan Result\n%s\n%d\n%s", name, age, hobby);
    fclose(fp);
    return 0;
}

Test.txt file:

Name:This is a test
Age:21
Hobby:Play games

When I run it:


Scan Result
`░
0
 >m
Process returned 0 (0x0)   execution time : 0.016 s
Press any key to continue.

So did I miss something? or it isn't possible? Answer with the code given would be very helpful for me to learn better, thank you.

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梦行七里 2025-02-14 21:10:09

％s读取单个单词，使用％[^\ n]读取所有内容，直到newline。

扫描到字符串时，请勿在数组名称之前放置＆amp;/code>。作为函数参数传递时，数组会自动衰减指针。

    fscanf(fp,"Name: %[^\n] Age: %d Hobby: %[^\n]",name,&age,hobby);

或使用fgets（）一次读取一行，然后您可以使用sscanf（）从中提取。

char line[100];
fgets(line, sizeof line, fp);
sscanf(line, "Name: %[^\n]", name);
fgets(line, sizeof line, fp);
sscanf(line, "Age: %d", &age);
fgets(line, sizeof line), fp;
sscanf(line, "Hobby: %[^\n]", hobby);

%s reads a single word, use %[^\n] to read everything until a newline.

Don't put & before array names when scanning into a string. Arrays automatically decay to a pointer when passed as a function argument.

    fscanf(fp,"Name: %[^\n] Age: %d Hobby: %[^\n]",name,&age,hobby);

Or use fgets() to read one line at a time, then you can use sscanf() to extract from it.

char line[100];
fgets(line, sizeof line, fp);
sscanf(line, "Name: %[^\n]", name);
fgets(line, sizeof line, fp);
sscanf(line, "Age: %d", &age);
fgets(line, sizeof line), fp;
sscanf(line, "Hobby: %[^\n]", hobby);

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