#include <stdio.h>
#include <stdlib.h>
int main(void) {
int i = 0;
char c, *input;
input = (char *) malloc(sizeof(char));
if(input == NULL) {
printf("NOT ENOUGH SPACE!");
exit(1);
}
printf("Input a string, press ENTER when done: ");
while((c = getchar()) != '\n') {
realloc(input, (sizeof(char)));
input[i++] = c;
}
input[i] = '\0';
printf("\nYou've entered the string: %s\n", input);
}
以上代码段适用于小输入。但只要提供的输入量很大,它就会失败。存在运行时错误或分段错误。 重新分配内存空间时可能会出现一些错误。 我基本上想要从用户动态存储一个字符数组,即没有提到用户可以直接放入任何大小的字符数组的输入容量。
答案 0 :(得分:2)
这里的逻辑是错误的:
while((c = getchar()) != '\n') {
realloc(input, (sizeof(char)));
input[i++] = c;
}
您实际上并没有增加缓冲区的大小,而且您也放弃了realloc
的结果。
尝试:
while ((c = getchar()) != '\n') {
// Note: you need one extra character for the terminator, so for the
// first char, when `i` is 0, then you need room for two `char`s in
// the buffer - one for the first input character and one for the
// terminator. And so on...
char * temp = realloc(input, i + 2); // NB: realloc can, and sometimes does, fail
if (temp == NULL) // if realloc failed then exit program
exit(1);
input = temp; // otherwise update input...
input[i++] = c;
}
<小时/> 此外,因为你总是会在每个角色上调用realloc(这是非常低效的,顺便说一句,但它有效),这一行:
input = (char *) malloc(sizeof(char));
(不应该有一个演员,BTW,因为这是C,而不是C ++)可以只是:
input = NULL;
<小时/> 最后一个错误:
char c;
应该是:
int c;
否则您的while
循环可能永远不会终止,因为EOF
只能正确表示为int
。
#include <stdio.h>
#include <stdlib.h>
int main(void) {
int i = 0;
int c;
char * input = NULL;
printf("Input a string, press ENTER when done: ");
while ((c = getchar()) != '\n') {
// Note: you need one extra character for the terminator, so for the
// first char, when `i` is 0, then you need room for two `char`s in
// the buffer - one for the first input character and one for the
// terminator. And so on...
char * temp = realloc(input, i + 2); // NB: realloc can, and sometimes does, fail
if (temp == NULL) // if realloc failed then exit program
exit(1);
input = temp; // otherwise update input...
input[i++] = c;
}
input[i] = '\0';
printf("\nYou've entered the string: %s\n", input);
return 0;
}