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Matt Bishop Office: 2209 Watershed Sciences Phone: +1 (530) 752-8060 Email: [email protected] |
Version of April 2, 2024 at 12:13PM
/*
* a more complicated program with function pointers
*
* Matt Bishop, ECS 36A
* -- May 22, 2024 original version
*/
#include <stdio.h>
#include <ctype.h>
#include <string.h>
/*
* first function: make everything upper case
*/
char *upper(char *str)
{
static char buf[1024]; /* buffer to return transformed string */
char *b; /* pointer to go through buf */
/* change all lower case letters to upper case */
for(b = buf; *str; b++, str++)
*b = toupper(*str);
/* return the internal. saved buffer */
return(buf);
}
/*
* second function: make everything lower case
*/
char *lower(char *str)
{
static char buf[1024]; /* buffer to return transformed string */
char *b; /* pointer to go through buf */
/* change all upper case letters to lower case */
for(b = buf; *str; b++, str++)
*b = tolower(*str);
/* return the internal. saved buffer */
return(buf);
}
/*
* the main function
*/
int main(void)
{
char inbuf[1024]; /* input buffer */
char *pin; /* used to scan the input buffer */
char *(*func)(char *); /* pointer to function to call */
/*
* loop, transforming the input
*/
while(printf("l/u/EOF> "), fgets(inbuf, 1024, stdin) != NULL){
/* fgets keeps the newline; we don't want it */
if (inbuf[strlen(inbuf)-1] == '\n')
inbuf[strlen(inbuf)-1] = '\0';
/* skip any leading white space */
pin = inbuf;
while(isspace(*pin))
pin++;
/* got a char -- interpret command */
/* note a NUL byte means nothing; */
/* go back and ask again */
switch(*pin++){
case '\0': /* NUL byte -- ignore line */
continue;
case 'u': /* transform to upper case */
case 'U':
func = upper;
break;
case 'l': /* transform to lower case */
case 'L':
func = lower;
break;
default: /* remind the user of good commands */
printf("Commands: l, u, EOF\n");
continue;
}
/* now skip any intervening space */
while(isspace(*pin))
pin++;
/* if there's no string, remind the user */
if (*pin == '\0'){
printf("input: [u | l] string or EOF\n");
continue;
}
/* do the transformation and print the result */
printf("'%s' becomes '%s'\n", pin, (*func)(pin));
}
/* bye! */
return(0);}
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ECS 36A, Programming & Problem Solving Version of April 2, 2024 at 12:13PM
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You can get the raw source code here.
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