C - cs50.h GetString 错误

Question

您好，我是编程界的新手，我正在尝试在线学习哈佛的 CS50 类(class)。在制作我的“Hello World”程序时，我下载了“cs50.h”来定义 GetString 和 string(至少我认为是这样)。所以这是我写的代码:

文件.c:

#include "cs50.h"
#include <stdio.h>

int main(int argc, string argv[])
{
    string name;
    printf("Enter your name: ");
    name = GetString();
    printf("Hello, %s\n", name);
}

但是，每当我尝试制作文件时，都会发生这种情况:

cc     file.c   -o file
Undefined symbols for architecture x86_64:
"_GetString", referenced from:
  _main in file-JvqYUC.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [file] Error 1

如果有帮助，这里是 cs50.h 文件的链接:http://dkui3cmikz357.cloudfront.net/library50/c/cs50-library-c-3.0/cs50.h

我想知道为什么会出现此错误以及如何修复它。请帮忙。

Answer 1

您似乎忘记了从 http://dkui3cmikz357.cloudfront.net/library50/c/cs50-library-c-3.0/cs50.c 下载并链接到项目 cs50.c 文件

*.h 通常只包含声明。 *.c(对于 C)和 *.cpp(对于 C++)包含实现。

这个类有GetSting函数实现:

string GetString(void)
{
    // growable buffer for chars
    string buffer = NULL;

    // capacity of buffer
    unsigned int capacity = 0;

    // number of chars actually in buffer
    unsigned int n = 0;

    // character read or EOF
    int c;

    // iteratively get chars from standard input
    while ((c = fgetc(stdin)) != '\n' && c != EOF)
    {
        // grow buffer if necessary
        if (n + 1 > capacity)
        {
            // determine new capacity: start at 32 then double
            if (capacity == 0)
                capacity = 32;
            else if (capacity <= (UINT_MAX / 2))
                capacity *= 2;
            else
            {
                free(buffer);
                return NULL;
            }

            // extend buffer's capacity
            string temp = realloc(buffer, capacity * sizeof(char));
            if (temp == NULL)
            {
                free(buffer);
                return NULL;
            }
            buffer = temp;
        }

        // append current character to buffer
        buffer[n++] = c;
    }

    // return NULL if user provided no input
    if (n == 0 && c == EOF)
        return NULL;

    // minimize buffer
    string minimal = malloc((n + 1) * sizeof(char));
    strncpy(minimal, buffer, n);
    free(buffer);

    // terminate string
    minimal[n] = '\0';

    // return string
    return minimal;
}