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How to let gets() work correctly?

kai kai over 15 years ago

IN C Starndard lib, use gets can input string form stdio.

for example, push [backspace] can remove the last char.

But when i use gets(), it keep backspace char (0x0B).

Parents

0 edPer Westermark over 15 years ago in reply to kai kai

Any reason why you missed the instruction how to post source code? Notice any difference in readability?

char *getstring(char *string) {
    char *pointer;
    INT ch;

    pointer = string;
    while (1) {
        ch = _getchar_lk();
        if (ch == EOF) {
            return NULL;
        }

        if (ch == 8) {
            if (pointer > string) {
                putchar('\b');
                putchar(' ');
                putchar('\b');
                pointer--;
            }
        } else if (ch == '\r' || ch =='\n' || ch >= ' ') {
            putchar(ch);
            if (ch == '\r') putchar('\n');
            if (ch == '\n' || ch == '\r') break;
            *pointer++ = ch;
        }
    }

    *pointer = 0;
    return string;
}

By the way - what happens if you have already received characters that you have stored in your string when you get an EOF?

Another thing - exactly how large is your string? What happens if someone enters moer characters than what will fit in string?

Reply

0 edPer Westermark over 15 years ago in reply to kai kai

Any reason why you missed the instruction how to post source code? Notice any difference in readability?

char *getstring(char *string) {
    char *pointer;
    INT ch;

    pointer = string;
    while (1) {
        ch = _getchar_lk();
        if (ch == EOF) {
            return NULL;
        }

        if (ch == 8) {
            if (pointer > string) {
                putchar('\b');
                putchar(' ');
                putchar('\b');
                pointer--;
            }
        } else if (ch == '\r' || ch =='\n' || ch >= ' ') {
            putchar(ch);
            if (ch == '\r') putchar('\n');
            if (ch == '\n' || ch == '\r') break;
            *pointer++ = ch;
        }
    }

    *pointer = 0;
    return string;
}

By the way - what happens if you have already received characters that you have stored in your string when you get an EOF?

Another thing - exactly how large is your string? What happens if someone enters moer characters than what will fit in string?

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