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我正在嘗試編寫一本書Beginning C 5th Ed的示例程序。通過Ivor Horton。試圖編譯它在OSX,我正從GCC以下的輸出:體系結構x86_64的未定義符號:「_gets_s」
$ gcc program6_07.c
program6_07.c:18:59: warning: format specifies type 'int' but the argument has
type 'size_t' (aka 'unsigned long') [-Wformat]
"Terminate input by entering an empty line:\n", str_len);
^~~~~~~
program6_07.c:23:5: warning: implicit declaration of function 'gets_s' is
invalid in C99 [-Wimplicit-function-declaration]
gets_s(buf, buf_len); // Read a lin...
^
program6_07.c:24:9: warning: implicit declaration of function 'strnlen_s' is
invalid in C99 [-Wimplicit-function-declaration]
if(!strnlen_s(buf, buf_len)) // Empty lin...
^
program6_07.c:27:8: warning: implicit declaration of function 'strcat_s' is
invalid in C99 [-Wimplicit-function-declaration]
if(strcat_s(str, str_len, buf)) // Concatenat...
^
program6_07.c:33:60: warning: data argument not used by format string
[-Wformat-extra-args]
printf("The words in the prose that you entered are:\n", str);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
program6_07.c:37:18: warning: implicit declaration of function 'strtok_s' is
invalid in C99 [-Wimplicit-function-declaration]
char * pWord = strtok_s(str, &str_len, delimiters, &ptr); // Find 1st word
^
program6_07.c:37:10: warning: incompatible integer to pointer conversion
initializing 'char *' with an expression of type 'int' [-Wint-conversion]
char * pWord = strtok_s(str, &str_len, delimiters, &ptr); // Find 1st word
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
program6_07.c:45:13: warning: incompatible integer to pointer conversion
assigning to 'char *' from 'int' [-Wint-conversion]
pWord = strtok_s(NULL, &str_len, delimiters, &ptr); // Find sub...
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8 warnings generated.
Undefined symbols for architecture x86_64:
"_gets_s", referenced from:
_main in program6_07-4a1c4c.o
"_strcat_s", referenced from:
_main in program6_07-4a1c4c.o
"_strnlen_s", referenced from:
_main in program6_07-4a1c4c.o
"_strtok_s", referenced from:
_main in program6_07-4a1c4c.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
程序的代碼如下:
// Program 6.7 Find all the words
#define __STDC_WANT_LIB_EXT1__ 1 // Make optional versions of functions available
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
int main(void)
{
char delimiters[] = " \".,;:!?)("; // Prose delimiters
char buf[100]; // Buffer for a line of keyboard input
char str[1000]; // Stores the prose to be tokenized
char* ptr = NULL; // Pointer used by strtok_s()
str[0] = '\0'; // Set 1st character to null
size_t str_len = sizeof(str);
size_t buf_len = sizeof(buf);
printf("Enter some prose that is less than %d characters.\n"
"Terminate input by entering an empty line:\n", str_len);
// Read multiple lines of prose from the keyboard
while(true)
{
gets_s(buf, buf_len); // Read a line of input
if(!strnlen_s(buf, buf_len)) // Empty line ends input
break;
if(strcat_s(str, str_len, buf)) // Concatenate the line with str
{
printf("Maximum permitted input length exceeded.");
return 1;
}
}
printf("The words in the prose that you entered are:\n", str);
// Find and list all the words in the prose
unsigned int word_count = 0;
char * pWord = strtok_s(str, &str_len, delimiters, &ptr); // Find 1st word
if(pWord)
{
do
{
printf("%-18s", pWord);
if(++word_count % 5 == 0)
printf("\n");
pWord = strtok_s(NULL, &str_len, delimiters, &ptr); // Find subsequent words
}while(pWord); // NULL ends tokenizing
printf("\n%u words found.\n", word_count);
}
else
printf("No words found.\n");
return 0;
}
我原以爲我已經定義的可選功能,但我猜我沒有?這只是一本過時的書或一個不好的例子,或者當我試圖編譯它時,我做錯了什麼?
而'__STDC_WANT_LIB_EXT1__'也是在C11中引入的嗎? –
@KeineLust:嚴格來說,它是由TR 24731-1技術報告引入的,但就標準而言,是的,它被添加到C11中。但是,您還必須檢查實現中是否定義了__STDC_LIB_EXT1__,以確定是否添加'__STDC_WANT_LIB_EXT1__'會產生任何影響。我不知道提供這個標準的Unix實現。另請參見[您是否使用TR 24731'安全'功能?](https://stackoverflow.com/questions/372980/do-you-use-the-tr-24731-safe-functions) –