Script started on Mon Oct 20 17:28:16 2025
macbook:logs> cd ../programs/C_ch13
macbook:C_ch13> echo attendance code 413
attendance code 413
macbook:C_ch13> man string
macbook:C_ch13> cat string_example.c 
#include <stdio.h>
#include <string.h>

int main(){
    char date1[] = {'J', 'u', 'n', 'e', ' ', '1', '4', '\0'}; 
    char date2[] = "October 18"; 

    // strcpy -> strncpy
    // strlen -> strnlen
    // strcat -> strncat

    // strcpy
    //strcpy(date1, date2);
    strncpy(date1, date2, 7);

    printf("%s \n", date1);
    printf("%s \n", date2);

   return 0;
}
macbook:C_ch13> gcc string_example.c
macbook:C_ch13> ./a.out
October 
October 18 
macbook:C_ch13> cp string_example.c str1.c
macbook:C_ch13> vi str1.c
macbook:C_ch13> gcc str1.c
macbook:C_ch13> ./a.out
date1: June 14 
date2: October 18 
 now we make a change
date1: October 
date2: October 18 
macbook:C_ch13> cat str1.c
#include <stdio.h>
#include <string.h>

int main(){
    char date1[] = {'J', 'u', 'n', 'e', ' ', '1', '4', '\0'}; 
    char date2[] = "October 18"; 

    printf("date1: %s \n", date1);
    printf("date2: %s \n", date2);

    printf(" now we make a change\n");
    // strcpy -> strncpy
    // strlen -> strnlen
    // strcat -> strncat

    // strcpy
    //strcpy(date1, date2);
    strncpy(date1, date2, 7);

    printf("date1: %s \n", date1);
    printf("date2: %s \n", date2);

   return 0;
}
macbook:C_ch13> gcc str1.c
macbook:C_ch13> ./a.out
date1: June 14 
date2: October 18 
 now we make a change
date1: October 
date2: October 18 
macbook:C_ch13> 
macbook:C_ch13> cat string_example2.c 
#include <stdio.h>
#include <string.h>

int main(){
    char date1[] = {'J', 'u', 'n', 'e', ' ', '1', '4', '\0'}; 
    char date2[] = "October 18"; 

    // strcpy -> strncpy
    // strlen -> strnlen
    // strcat -> strncat

    // strcpy
    //strcpy(date1, date2);
    int c = strncmp(date1, date2, 7);

    printf("%s \n", date1);
    printf("%s \n", date2);
    printf("cmp returns %d \n", c);

    c = strncmp(date1, date1, 7);
    printf("cmp returns %d \n", c);

   return 0;
}
macbook:C_ch13> gcc string_example2.c 
macbook:C_ch13> ./a.out
June 14 
October 18 
cmp returns -5 
cmp returns 0 
macbook:C_ch13> cp string_example2.c string_example2b.c
macbook:C_ch13> vi string_example2b.c 
macbook:C_ch13> gcc string_example2b.c 
macbook:C_ch13> ./a.out
June 14 
October 18 
cmp(date1, date2) returns -5 
cmp(date2, date1) returns 5 
cmp(date1, date1)  returns 0 
macbook:C_ch13> cp string_example2b.c string_example2c.c
macbook:C_ch13> vi string_example2c.c
macbook:C_ch13> cat string_example2c.c 
#include <stdio.h>
#include <string.h>

int main(){
    char date1[] = "Octobeq 18";
    char date2[] = "October 18"; 

    // strcpy -> strncpy
    // strlen -> strnlen
    // strcat -> strncat

    // strcpy
    //strcpy(date1, date2);
    int c = strncmp(date1, date2, 7);

    printf("%s \n", date1);
    printf("%s \n", date2);
    printf("cmp(date1, date2) returns %d \n", c);
    c = strncmp(date2, date1, 7);
    printf("cmp(date2, date1) returns %d \n", c);

    c = strncmp(date1, date1, 7);
    printf("cmp(date1, date1)  returns %d \n", c);

   return 0;
}
macbook:C_ch13> gcc string_example2c.c
macbook:C_ch13> ./a.out
Octobeq 18 
October 18 
cmp(date1, date2) returns -1 
cmp(date2, date1) returns 1 
cmp(date1, date1)  returns 0 
macbook:C_ch13> cp string_example2c.c string_example2d.c
macbook:C_ch13> vi string_example2d.c
macbook:C_ch13> gcc string_example2d.c
macbook:C_ch13> ./a.out
abcdef 
abc 
cmp(date1, date2) returns 100 
cmp(date2, date1) returns -100 
cmp(date1, date1)  returns 0 
macbook:C_ch13> cat string_example2d.c
#include <stdio.h>
#include <string.h>

int main(){
    char date1[10] = "abcdef";
    char date2[10] = "abc"; 

    // strcpy -> strncpy
    // strlen -> strnlen
    // strcat -> strncat

    // strcpy
    //strcpy(date1, date2);
    int c = strncmp(date1, date2, 7);

    printf("%s \n", date1);
    printf("%s \n", date2);
    printf("cmp(date1, date2) returns %d \n", c);
    c = strncmp(date2, date1, 7);
    printf("cmp(date2, date1) returns %d \n", c);

    c = strncmp(date1, date1, 7);
    printf("cmp(date1, date1)  returns %d \n", c);

   return 0;
}
macbook:C_ch13> vi what_will_be.c
macbook:C_ch13> gcc what_will_be.c
what_will_be.c:6:8: error: use of undeclared identifier 's1'
    6 | strcpy(s1,"computer");
      |        ^
what_will_be.c:6:8: error: use of undeclared identifier 's1'
what_will_be.c:7:8: error: use of undeclared identifier 's2'
    7 | strcpy(s2,"science");
      |        ^
what_will_be.c:7:8: error: use of undeclared identifier 's2'
what_will_be.c:8:12: error: use of undeclared identifier 's1'
    8 | if (strcmp(s1,s2) < 0)
      |            ^
what_will_be.c:8:15: error: use of undeclared identifier 's2'
    8 | if (strcmp(s1,s2) < 0)
      |               ^
what_will_be.c:9:8: error: use of undeclared identifier 's1'
    9 | strcat(s1,s2);
      |        ^
what_will_be.c:9:11: error: use of undeclared identifier 's2'
    9 | strcat(s1,s2);
      |           ^
what_will_be.c:9:8: error: use of undeclared identifier 's1'
    9 | strcat(s1,s2);
      |        ^
what_will_be.c:11:8: error: use of undeclared identifier 's2'
   11 | strcat(s2,s1);
      |        ^
what_will_be.c:11:11: error: use of undeclared identifier 's1'
   11 | strcat(s2,s1);
      |           ^
what_will_be.c:11:8: error: use of undeclared identifier 's2'
   11 | strcat(s2,s1);
      |        ^
what_will_be.c:12:1: error: use of undeclared identifier 's1'
   12 | s1[strlen(s1) - 6]='\0';
      | ^
what_will_be.c:12:11: error: use of undeclared identifier 's1'
   12 | s1[strlen(s1) - 6]='\0';
      |           ^
what_will_be.c:13:25: error: use of undeclared identifier 's1'
   13 | printf(" s1 is [%s]\n", s1);
      |                         ^
15 errors generated.
macbook:C_ch13> vi what_will_be.c 
macbook:C_ch13> gcc what_will_be.c
macbook:C_ch13> ./a.out
 s1 is [computers]
macbook:C_ch13> vi what_will_be.c 
macbook:C_ch13> gcc what_will_be.c
macbook:C_ch13> ./a.out           
s1 is [computer]
s2 is [science]
After strcat
s1 is [computerscience]
s2 is [science]
After inserting null char
s1 is [computers]
s2 is [science] (same as before) 
macbook:C_ch13> cat what_will_be.c 
#include <stdio.h>
#include <string.h>

int main() {

char s1[100];
char s2[100];

strcpy(s1,"computer");
strcpy(s2,"science");

printf("s1 is [%s]\n", s1);
printf("s2 is [%s]\n", s2);

if (strcmp(s1,s2) < 0)
strcat(s1,s2);
else
strcat(s2,s1);

printf("After strcat\n");
printf("s1 is [%s]\n", s1);
printf("s2 is [%s]\n", s2);


s1[strlen(s1) - 6]='\0';
printf("After inserting null char\n");
printf("s1 is [%s]\n", s1);
printf("s2 is [%s] (same as before) \n", s2);

return 0;}

macbook:C_ch13> cd ../C_ch16
macbook:C_ch16> grep build *.c
C_ch16_6.c:struct part build_part(int number,
macbook:C_ch16> cat C_ch16_6.c 
struct part build_part(int number,
                const char * name, int on_hand)
{
    struct part p;
    p.number = number;
    strcpy(p.name, name);
    p.on_hand = on_hand;
    return p;
}

macbook:C_ch16> cp C_ch16_6.c struct_return.c
macbook:C_ch16> vi struct_return.c 
macbook:C_ch16> gcc struct_return.c 
struct_return.c:6:13: error: use of undeclared identifier 'NAME_LEN'
    6 |   char name[NAME_LEN + 1];
      |             ^
struct_return.c:15:17: error: variable has incomplete type 'struct part'
   15 |     struct part p;
      |                 ^
struct_return.c:15:12: note: forward declaration of 'struct part'
   15 |     struct part p;
      |            ^
2 errors generated.
macbook:C_ch16> vi struct_return.c           
macbook:C_ch16> gcc struct_return.c
struct_return.c:6:13: error: use of undeclared identifier 'NAME_LEN'
    6 |   char name[NAME_LEN + 1];
      |             ^
1 error generated.
macbook:C_ch16> vi struct_return.c 
macbook:C_ch16> gcc struct_return.c
macbook:C_ch16> ./a.out
  number 3
  name [abc]
  onhand 1
macbook:C_ch16> exit

Saving session...
...copying shared history...
...saving history...truncating history files...
...completed.
Deleting expired sessions...       2 completed.

Script done on Mon Oct 20 18:45:33 2025