reversewords.c #include <stdio.h> #include <string.h> #include <stdlib.h> #defin

Question

reversewords.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define STRLEN 80

int read_line(char line[], int len);
void reverse_words(char* line);

int main(void) {
char line[STRLEN+1];

printf("Enter a line of text: ");
read_line(line, STRLEN);

reverse_words(line);

puts(line);

return 0;
}

int read_line(char line[], int len) {
int ch, i = 0;

while ((ch = getchar()) != ' ')
    if (i < len)
      line[i++] = ch;

line[i] = '';

return i;
}

void reverse_words(char* line) {
int len;
char* buffer;
int read_pos, write_pos, word_start, word_end;

len = strlen(line);
buffer = malloc(__________);
if (buffer == NULL) {
    printf("out of memory in reverse_words. ");
    exit(EXIT_FAILURE);
}

read_pos = len - 1;
write_pos = 0;

while (read_pos >= 0) {
    if (line[read_pos] == ' ') {
      buffer[write_pos++] = line[read_pos--];
    }
    else {
      word_end = read_pos;

      while (read_pos >= 0 && line[read_pos] != ' ')
        read_pos--;

      word_start = read_pos + 1;

      while (word_start <= word_end)
        buffer[write_pos++] = line[_____________];
    }
}

buffer[write_pos] = '';
strcpy(line, buffer);

____________________;
}

Explanation / Answer

// C code
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define STRLEN 80
int read_line(char line[], int len);
void reverse_words(char* line);
int main(void) {
char line[STRLEN+1];
printf("Enter a line of text: ");
read_line(line, STRLEN);
reverse_words(line);
puts(line);
return 0;
}
int read_line(char line[], int len) {
int ch, i = 0;
while ((ch = getchar()) != ' ')
if (i < len)
line[i++] = ch;
line[i] = '';
return i;
}
void reverse_words(char* line) {
int len;
char* buffer;
int read_pos, write_pos, word_start, word_end;
len = strlen(line);
// memory allocation
buffer = malloc(sizeof(len));
if (buffer == NULL) {
printf("out of memory in reverse_words. ");
exit(EXIT_FAILURE);
}
read_pos = len - 1;
write_pos = 0;
while (read_pos >= 0) {
if (line[read_pos] == ' ') {
buffer[write_pos++] = line[read_pos--];
}
else {
word_end = read_pos;
while (read_pos >= 0 && line[read_pos] != ' ')
read_pos--;
word_start = read_pos + 1;
while (word_start <= word_end)
buffer[write_pos++] = line[word_start++];
   // increase word_start until it is equal to work_end
}
}
buffer[write_pos] = '';
strcpy(line, buffer);
//NOTHING TO BE ADDDED ON THIS LINE;
}

/*
output:

Enter a line of text:
james Anderson
Anderson james

*/

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