《操作系统》的实验代码。
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#include <stdio.h>
#define BUFSIZE 1024
static char buf[BUFSIZE];
/* *
* readline - get a line from stdin
* @prompt: the string to be written to stdout
*
* The readline() function will write the input string @prompt to
* stdout first. If the @prompt is NULL or the empty string,
* no prompt is issued.
*
* This function will keep on reading characters and saving them to buffer
* 'buf' until '\n' or '\r' is encountered.
*
* Note that, if the length of string that will be read is longer than
* buffer size, the end of string will be discarded.
*
* The readline() function returns the text of the line read. If some errors
* are happened, NULL is returned. The return value is a global variable,
* thus it should be copied before it is used.
* */
char *
readline(const char *prompt) {
if (prompt != NULL) {
cprintf("%s", prompt);
}
int i = 0, c;
while (1) {
c = getchar();
if (c < 0) {
return NULL;
}
else if (c >= ' ' && i < BUFSIZE - 1) {
cputchar(c);
buf[i ++] = c;
}
else if (c == '\b' && i > 0) {
cputchar(c);
i --;
}
else if (c == '\n' || c == '\r') {
cputchar(c);
buf[i] = '\0';
return buf;
}
}
}