kdeng00
120 lines
2.4 KiB
C
120 lines
2.4 KiB
C
/*
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*
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* Exercise 3-2. Write a function escape(s,t) that converts characters like
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* newline and tab into visible escape sequences like '\n' and '\t' as it
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* copies the string t to s. Use a switch. Write a function for the other
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* direction as well, converting escape sequences into real characters.
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*
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* Author: Kun Deng
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*/
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#include <stdio.h>
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#define ARRAY_SIZE 10
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#define BUFFER_SIZE (ARRAY_SIZE * 2)
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// Copies string t to s but the escape sequences
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// will be visible
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void escape(char *s, char *t);
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// Copies string t to s but the escape sequences
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// will be their real characters
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void ensnare(char *s, char *t);
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int main()
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{
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printf("Enter characters:\n");
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char unproccessed[ARRAY_SIZE];
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char escaped[BUFFER_SIZE];
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char ensared[ARRAY_SIZE];
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char c;
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int i;
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for (i = 0; i != ARRAY_SIZE; ++i)
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{
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c = getchar();
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if (c == EOF)
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{
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--i;
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continue;
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}
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unproccessed[i] = c;
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}
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unproccessed[i] = '\0';
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printf("\n\nUnproccessed string: %s\n", unproccessed);
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escape(escaped, unproccessed);
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printf("\n\nEscaped sequences replaced string: %s\n", escaped);
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ensnare(ensared, escaped);
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printf("\n\nEscaped sequences returned string: %s\n", ensared);
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return 0;
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}
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void escape(char *s, char *t)
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{
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int j = 0;
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char c;
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for (int i = 0; ((c = t[i])) != '\0'; ++i, ++j)
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{
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switch (c)
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{
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case '\n':
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s[j++] = '\\';
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s[j] = 'n';
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break;
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case '\t':
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s[j++] = '\\';
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s[j] = 't';
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break;
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default:
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s[j] = c;
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break;
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}
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}
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s[j] = '\0';
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}
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void ensnare(char *s, char *t)
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{
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int j = 0;
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// If one that means the previous character was the beginning of an escape
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// sequence
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int escape_found = 0;
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char c;
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char rr[] = "thecarinspace\0";
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for (int i = 0; ((c = t[i])) != '\0'; ++i, ++j)
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{
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switch (c)
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{
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case '\\':
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escape_found = 1;
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--j;
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break;
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case 'n':
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s[j] = (escape_found == 1) ? 10 : c;
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escape_found = 0;
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break;
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case 't':
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s[j] = (escape_found == 1) ? 9 : c;
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escape_found = 0;
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break;
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default:
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s[j] = c;
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break;
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}
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}
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s[j] = '\0';
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}
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