diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000000000000000000000000000000000000..70e34ecb3dcc4c74a1f8635625e280b492849b5e
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+ "C_Cpp.errorSquiggles": "disabled"
+}
\ No newline at end of file
diff --git a/a.out b/a.out
index 6077ca89373cb8457763dcffb1492b09a6f5d2d1..c1322169f1ed84f5f1b6ee06571f89c6eefbff13 100755
Binary files a/a.out and b/a.out differ
diff --git a/bool.h b/bool.h
new file mode 100644
index 0000000000000000000000000000000000000000..a30b9c2ca67d1a74a47e7f34cae669ffbeb6924e
--- /dev/null
+++ b/bool.h
@@ -0,0 +1 @@
+typedef enum {false, true} bool;
diff --git a/charptr.c b/charptr.c
new file mode 100644
index 0000000000000000000000000000000000000000..02384d3af4c9316071cebe0e82fa9c6cf0537c2f
--- /dev/null
+++ b/charptr.c
@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <string.h>
+
+void replace(char *subject, char search, char replace){
+ for(int i=0;;i++){
+ // if(*(subject+i) == search){
+ // *(subject+i) = replace;
+ // }
+ // if(*(subject+i) == '\0'){
+ // break;
+ // }
+
+ if(subject[i] == search){
+ subject[i] = replace;
+ }
+ if(subject[i] == '\0'){
+ break;
+ }
+ }
+}
+
+int main(){
+ //All arrays are pointers, all pointers are arrays
+
+ // char a[5];
+ // scanf("%s", a);
+
+ // int b;
+ // scanf("%d", &b);
+
+ char subject[] = "Hello World";
+ printf("Addr of index 1: %p\n", &subject[0]);
+ printf("Value of %p \n", subject);
+
+ // for(int i=0; i<strlen(subject); i++){
+ // printf("Value of subject[%d] = %c \n", i, subject[i]);
+ // printf("Address of subject[%d] = %p\n", i, &subject[i]);
+ // }
+ // printf("-------------------------------------------\n");
+ // for(int i=0; i<strlen(subject); i++){
+ // printf("Value of subject[%d] = %c \n", i, *(subject + i));
+ // printf("Address of subject[%d] = %p\n", i, subject + i);
+ // }
+
+ replace(subject, 'o', 'i');
+
+ printf("After replacing: %s\n", subject);
+}
\ No newline at end of file
diff --git a/constch.c b/constch.c
new file mode 100644
index 0000000000000000000000000000000000000000..311aea9b93f8c70c1b184c43a05085a697c8c182
--- /dev/null
+++ b/constch.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+int main() {
+ const int x = 10; // x is a const variable
+ int *ptr = &x; // cast away the const-ness
+
+ *ptr = 20; // modify the value of x through ptr
+
+ printf("x = %d\n", x); // The value of x is now modified
+
+ return 0;
+}
diff --git a/consts.c b/consts.c
new file mode 100644
index 0000000000000000000000000000000000000000..c602a8f33b6039cd4ba220a4801096d6645f44be
--- /dev/null
+++ b/consts.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+int main(){
+ int i = 10; //variable
+ const int j = 20;
+
+ int *danger = (int *)(&j); //cast-away the constness
+ *danger = 50;
+ *danger = 100;
+
+ printf("const j = %d", j);
+}
\ No newline at end of file
diff --git a/helloworld b/helloworld
new file mode 100755
index 0000000000000000000000000000000000000000..c9def79d1d3e1fd140cfd078c3cdbb140f8f8b10
Binary files /dev/null and b/helloworld differ
diff --git a/main.c b/main.c
new file mode 100644
index 0000000000000000000000000000000000000000..e653957c09371f587dd842fb78cd0f5e617b92ca
--- /dev/null
+++ b/main.c
@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <unistd.h>
+#include "bool.h"
+#include "weekday.h"
+//int, char, float - primitive
+//bool - 0 - false, 1 - true
+bool is_holiday(weekday today);
+
+int main() {
+ if(is_holiday(SUN)){
+ printf("Holiday \n");
+ } else {
+ printf("Not Holiday \n");
+ }
+
+}
+
+bool is_holiday(today) weekday today=1; {
+ switch(today) {
+ case SUN:
+ return true;
+ break;
+ case SAT:
+ return true;
+ break;
+ default:
+ return false;
+ }
+}
\ No newline at end of file
diff --git a/memhook b/memhook
new file mode 100755
index 0000000000000000000000000000000000000000..6d05044353ea5ece365463cc7d2568cc9f9d36e3
Binary files /dev/null and b/memhook differ
diff --git a/memhook.c b/memhook.c
new file mode 100644
index 0000000000000000000000000000000000000000..2c59772e436586731801a3c89d2d8b462030dc4b
--- /dev/null
+++ b/memhook.c
@@ -0,0 +1,78 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/uio.h>
+#include <unistd.h>
+#include <errno.h>
+
+// Function to write data to another process' memory
+void write_data_to_address(pid_t pid, void *remote_addr, const void *data, size_t size) {
+ struct iovec local[1];
+ struct iovec remote[1];
+
+ local[0].iov_base = (void*) data;
+ local[0].iov_len = size;
+ remote[0].iov_base = remote_addr;
+ remote[0].iov_len = size;
+
+ ssize_t bytes_written = process_vm_writev(pid, local, 1, remote, 1, 0);
+ if (bytes_written == -1) {
+ perror("process_vm_writev");
+ exit(1);
+ } else if (bytes_written != size) {
+ fprintf(stderr, "Partial write: %ld of %zu bytes\n", bytes_written, size);
+ exit(1);
+ }
+}
+
+// Function to get the base address of the writable segment from /proc/<pid>/maps
+void* get_base_address(pid_t pid) {
+ char filename[64];
+ FILE *f;
+ void* base_address = NULL;
+ char line[256];
+
+ snprintf(filename, sizeof(filename), "/proc/%d/maps", pid);
+ f = fopen(filename, "r");
+ if (f == NULL) {
+ perror("fopen");
+ exit(1);
+ }
+
+ while (fgets(line, sizeof(line), f)) {
+ if (strstr(line, "rw-p") && strstr(line, "/var/labsstorage/home/sibidharan/c-for-hackers/helloworld")) {
+ sscanf(line, "%p-%*p", &base_address);
+ break;
+ }
+ }
+
+ fclose(f);
+ return base_address;
+}
+
+int main(int argc, char *argv[]) {
+ if (argc != 3) {
+ fprintf(stderr, "Usage: %s <pid> <offset>\n", argv[0]);
+ return 1;
+ }
+
+ pid_t pid = atoi(argv[1]);
+ size_t offset = strtoull(argv[2], NULL, 0); // Target offset in the remote process
+ char *new_string = "Sibid";
+
+ // Get the base address of the writable segment
+ void *base_address = get_base_address(pid);
+ if (base_address == NULL) {
+ fprintf(stderr, "Could not find base address\n");
+ return 1;
+ }
+
+ // Calculate the real address
+ void *real_address = (void*)((char*)base_address + offset);
+
+ // Write new string to the target process' memory
+ write_data_to_address(pid, real_address, new_string, strlen(new_string) + 1);
+
+ printf("Successfully wrote '%s' to address %p in process %d\n", new_string, real_address, pid);
+ return 0;
+}
diff --git a/nonop.c b/nonop.c
new file mode 100644
index 0000000000000000000000000000000000000000..4ba2dee4d1f23c51cb7314f6dcdf9f9d432601ee
--- /dev/null
+++ b/nonop.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include <unistd.h>
+
+
+int is_holiday(int t){
+ switch(t) {
+ case 0: //SUNDAY
+ return 1;
+ break;
+ case 6: // SATURDAY
+ return 1;
+ break;
+ default:
+ return 0;
+ }
+}
+
+int main() {
+ if(is_holiday(2)){
+ printf("Holiday \n");
+ } else {
+ printf("Not Holiday \n");
+ }
+
+}
\ No newline at end of file
diff --git a/pointer.c b/pointer.c
new file mode 100644
index 0000000000000000000000000000000000000000..24e4ff6766f056233d103052ecf2ca614e9f28c3
--- /dev/null
+++ b/pointer.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+int increment(int i){ //the data is duplicated into i for processing
+ i = i + 1; //11
+ return i;
+}
+
+void decrement(int *i){ // no new data is created instead just the pointer is stored
+ *i = *i - 1;
+}
+
+int main() {
+ int a = 10 b = 15;
+ int *p = &a; //initialization synatx
+ int *c = p; // *(&p)
+
+ a = increment(a); // 2 variables are used
+
+ printf("After increment: %d\n", a); // 10
+ printf("Value of a: %d\n", a); // 11
+
+ decrement(&a); //or &a only one variable is used
+
+ printf("After decrement: %d\n", a);
+ printf("Value of a: %d\n", a); // 11
+
+ // printf("Value of p = %p \n", p);
+ // printf("Address of p = %p \n", &p);
+
+ // printf("Value of a = %d \n", a);
+ // printf("Address of a = %p \n", &a);
+
+ // printf("Value of p = %p \n", p);
+ // printf("Address of p = %p \n", &p); //this is useless
+
+ // printf("Pointed value of p = %d \n", *p);
+
+ // p = &a; //i change the address stored in p
+ // *p = 20; //change the value in address stored in p
+
+ // printf("Value of p = %p \n", p);
+ // printf("Address of p = %p \n", &p);
+
+ // printf("Value of a = %d \n", a);
+
+ // printf("Challenge: %d", *(&a));
+
+ // printf("%d", *c);
+
+}
\ No newline at end of file
diff --git a/weekday.h b/weekday.h
new file mode 100644
index 0000000000000000000000000000000000000000..35c07a0f6efca81b1279dde4918d3cff8eeb3420
--- /dev/null
+++ b/weekday.h
@@ -0,0 +1 @@
+typedef enum day {SUN, MON, TUE, WED, THU, FRI, SAT} weekday; //a set of named integer constants