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#include <stdio.h>
/* The C Programming Language: 2nd Edition
*
* Exercise 3-2: Write a function escape(s,t) that converts characters like
* newline and tab into visible escape sequences like \n and \t as it copies
* the string t to s. Use a switch. Write a function for the other direction
* as well, converting escape sequences into the real characters.
*
* Answer: Fun! Switches can be used as shorthand if-else chains.
*/
#define STRMAX 80
void escape(char s[], char t[]) {
// i for t, j for s
int i, j;
j = 0;
for (i = 0; t[i] != '\0'; i++) {
switch(t[i]) {
case '\n':
s[j++] = '\\';
s[j++] = 'n';
break;
case '\t':
s[j++] = '\\';
s[j++] = 't';
break;
default:
s[j++] = t[i];
break;
}
}
s[j] = '\0';
}
void unescape(char s[], char t[]) {
// i for t, j for s
int i, j;
j = 0;
for (i = 0; t[i] != '\0'; i++) {
if (t[i] == '\\') {
switch (t[i + 1]) {
case 'n':
s[j++] = '\n';
break;
case 't':
s[j++] = '\t';
break;
}
} else {
s[j++] = t[i];
}
}
s[j] = '\0';
}
int main() {
char src[STRMAX] = "foo\nbar\t\tbaz\nnozzle";
char dest[STRMAX] = "";
/* Let's escape it... */
escape(dest, src);
printf("%s\n", dest);
/* ...and unescape it! */
unescape(dest, src);
printf("%s\n", dest);
return 0;
}
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