listing 1
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isalnum(ch)) printf("%c is alphanumeric\n", ch); 
  } 
 
  return 0; 
}

listing 2
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isalpha(ch)) printf("%c is a letter\n", ch); 
  } 
 
  return 0; 
}

listing 3
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isascii(ch)) printf("%c is ASCII defined\n", ch); 
  } 
 
  return 0; 
}

listing 4
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(iscntrl(ch)) printf("%c is a control character\n", ch); 
  } 
 
  return 0; 
}

listing 5
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isdigit(ch)) printf("%c is a digit\n", ch); 
  } 
 
  return 0; 
}

listing 6
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isgraph(ch)) printf("%c is a printing character\n", ch); 
  } 
 
  return 0; 
}

listing 7
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(islower(ch)) printf("%c is lowercase\n", ch); 
  } 
 
  return 0; 
}

listing 8
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isprint(ch)) printf("%c is printable\n", ch); 
  } 
 
  return 0; 
}

listing 9
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(ispunct(ch)) printf("%c is punctuation\n", ch); 
  } 
 
  return 0; 
}

listing 10
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch=='.') break; 
    if(isspace(ch)) printf("%c is white-space\n", ch); 
  } 
 
  return 0; 
}

listing 11
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isupper(ch)) printf("%c is upper-case\n", ch); 
  } 
 
  return 0; 
}

listing 12
#include <ctype.h> 
#include <stdio.h> 
 
int main(void) 
{ 
  char ch; 
 
  for(;;) { 
    ch = getchar(); 
    if(ch==' ') break; 
    if(isxdigit(ch)) printf("%c is hexadecimal \n", ch); 
  } 
 
  return 0; 
}

listing 13
char str[20], out[20]; 
strcpy(str, "hello there"); 
memccpy(out, str,' ', 20);

listing 14
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  void *p; 
 
  p = memchr("this is a test", ' ', 14); 
  printf((char *) p); 
 
  return 0; 
}

listing 15
#include <stdio.h> 
#include <string.h> 
 
int main(int argc, char *argv[]) 
 
{ 
  int outcome; 
  size_t len, l1, l2; 
 
  if(argc != 3) { 
    printf("Use two command-line args."); 
    return 1; 
  } 
 
  /* find the length of shortest */ 
  len = (l1=strlen(argv[1]))<(l2=strlen(argv[2])) ? l1:l2; 
 
  outcome = memcmp(argv[1], argv[2], len); 
  if(!outcome) printf("equal"); 
  else if(outcome<0) printf("First less than second.\n"); 
  else printf("First greater than second\n"); 
 
  return 0; 
}

listing 16
#include <stdio.h> 
#include <string.h> 
#define SIZE 80 
 
int main(void) 
{ 
  char buf1[SIZE], buf2[SIZE]; 
 
  strcpy(buf1, "When, in the course of..."); 
  memcpy(buf2, buf1, SIZE); 
  printf(buf2); 
 
  return 0; 
}

listing 17
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char str1[40], str2[40]; 
 
  strcpy(str1, "Born to code in C/C++."); 
  memmove(str2, str1, strlen(str1)+1); 
  printf(str2); 
 
  return 0; 
}

listing 18
memset(buf, '\0', 100); 
memset(buf, 'X', 10); 
printf((char *) buf);

listing 19
char str[8]; 
stpcpy(str, "hello");

listing 20
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char s1[80], s2[80]; 
 
  gets(s1); 
  gets(s2); 
 
  strcat(s2, s1); 
  printf(s2); 
 
  return 0; 
}

listing 21
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char *p; 
 
  p = strchr("this is a test", ' '); 
  printf(p); 
 
  return 0; 
}

listing 22
int password(void) 
{ 
  char s[80]; 
 
  printf("Enter password: "); 
  gets(s); 
  if(strcmp(s, "pass")) { 
    printf("Invalid password.\n"); 
    return 0; 
  } 
  return 1; 
}

listing 23
char str[80]; 
strcpy(str, "hello");

listing 24
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  int len; 
 
  len = strcspn("this is a test", "ab"); 
  printf("%d", len); 
 
  return 0; 
}

listing 25
char str[80], *p; 
strcpy(str, "this is a test"); 
p = strdup(str);

listing 26
void swap() 
{ 
  /* ... */ 
  if(error) printf(_strerror("Error in swap."));

listing 27
if(errno) printf(strerror(errno));

listing 28
#include <stdio.h> 
#include <string.h> 
 
int main(int argc, char *argv[]) 
{ 
 
  if(argc != 3) { 
    printf("Use two command-line args."); 
    return 1; 
  } 
 
  if(!stricmp(argv[1], argv[2])) 
    printf("The filenames are the same.\n"); 
  else 
    printf("The filenames differ.\n"); 
 
  return 0; 
}

listing 29
strcpy(s, "hello"); 
printf("%d", strlen(s));

listing 30
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char s[80]; 
 
  strcpy(s, "THIS IS A TEST"); 
  strlwr(s); 
  printf(s); 
 
  return 0; 
}

listing 31
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char s1[80], s2[80]; 
  size_t len; 
 
  gets(s1); 
  gets(s2); 
 
  /* compute how many chars will actually fit */ 
  len = 79-strlen(s2); 
 
  strncat(s2, s1, len); 
  printf(s2); 
 
  return 0; 
}

listing 32
#include <stdio.h> 
#include <string.h> 
 
int main(int argc, char *argv[]) 
{ 
  if(argc != 3) { 
    printf("Use two command-line args."); 
    return 1; 
  } 
 
  if(!strnicmp(argv[1], argv[2], 8)) 
    printf("The filenames are the same.\n"); 
  else 
    printf("The filenames differ.\n"); 
 
  return 0; 
}

listing 33
char str1[128], str2[80]; 
gets(str1); 
strncpy(str2, str1, 79);

listing 34
strnset(str, 'x', 10);

listing 35
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char *p; 
 
  p = strpbrk("this is a test", " absj"); 
  printf(p); 
 
  return 0; 
}

listing 36
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char *p; 
 
  p = strrchr("this is a test", 'i'); 
  printf(p); 
 
  return 0; 
}

listing 37
#include <stdio.h> 
#include <string.h> 
 
char s[] = "hello"; 
 
int main(void) 
{ 
  strrev(s); 
  printf(s); 
 
  return 0; 
}

listing 38
strset(str, 'x');

listing 39
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  int len; 
 
  len = strspn("this is a test", "siht "); 
  printf("%d",len); 
 
  return 0; 
}

listing 40
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char *p; 
 
  p = strstr("this is a test", "is"); 
  printf(p); 
 
  return 0; 
}

listing 41
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char *p; 
 
  p = strtok("The summer soldier, the sunshine patriot"," "); 
  printf(p); 
  do { 
    p=strtok('\0', ", "); 
    if(p) printf("|%s", p); 
  } while(p); 
 
  return 0; 
}

listing 42
#include <stdio.h> 
#include <string.h> 
 
int main(void) 
{ 
  char s[80]; 
 
  strcpy(s, "this is a test"); 
  strupr(s); 
  printf(s); 
 
  return 0; 
}

listing 43
putchar(tolower('Q'));

listing 44
putchar(toupper('a'));