测试扩展名是否一致

[qhmilanista]

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

#define N 10

void get_extension(const char *file_name, char *extension);
bool test_extension(const char *file_name, const char *extension);

int main(void)
{
	char extension[N] = "TXT";
	const char *file_name = "memo.txt";
	bool final = test_extension(file_name, extension);
	printf("%d\n", final);
	
	return 0;
}

void get_extension(const char *file_name, char *extension)
{
	int n = 0;
	for(; *file_name != '\0'; file_name++){
		if(*file_name == '.'){
			n = 1;
			break;
		}	
		else 
			n = 0;
	}
	if( n == 1){
	file_name++;
	extension = malloc(strlen(file_name));
	if(extension == NULL){
		printf("Error,malloc failed\n");
		exit (EXIT_FAILURE);
	}	
	strcpy(extension, file_name);
	}
	else{
	extension = malloc(strlen(file_name));
	if(extension == NULL){
		printf("Error,malloc failed\n");
		exit (EXIT_FAILURE);
	}
	extension = '\0';
	}				
}


bool test_extension(const char *file_name, const char *extension)
{
	char *ex, up[N];
	ex = malloc(strlen(file_name));
	if(ex == NULL){
		printf("Error,malloc failed\n");
		exit (EXIT_FAILURE);
	}
	int t = 0;
	get_extension(file_name, ex);
	int i;
	for(i = 0; ex[i] != '\0'; i++)
		up[i] = toupper(ex[i]);
		
	int deci = strcmp(up, extension);
	if(deci == 0)
	return true;

	return false;
}		
		
		

为什么测试失败，是0---false
在下就是想file_name指向包含文件名的字符串。如果文件的扩展名与extension指向的字符串匹配（不区分大小写），函数返回true。例如，函数调用test_extension("memo.txt", TXT)将返回true