First Commit.

.idea/C-Stuff.iml

+<?xml version="1.0" encoding="UTF-8"?>
+<module classpath="CMake" type="CPP_MODULE" version="4" />
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.idea/codeStyles/Project.xml

+<component name="ProjectCodeStyleConfiguration">
+  <code_scheme name="Project" version="173">
+    <Objective-C-extensions>
+      <file>
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Import" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Macro" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Typedef" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Enum" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Constant" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Global" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Struct" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="FunctionPredecl" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Function" />
+      </file>
+      <class>
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Property" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Synthesize" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InitMethod" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="StaticMethod" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InstanceMethod" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="DeallocMethod" />
+      </class>
+      <extensions>
+        <pair source="cpp" header="h" fileNamingConvention="NONE" />
+        <pair source="c" header="h" fileNamingConvention="NONE" />
+      </extensions>
+    </Objective-C-extensions>
+  </code_scheme>
+</component>
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.idea/misc.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CMakeWorkspace" PROJECT_DIR="$PROJECT_DIR$" />
+</project>
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.idea/modules.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/C-Stuff.iml" filepath="$PROJECT_DIR$/.idea/C-Stuff.iml" />
+    </modules>
+  </component>
+</project>
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.idea/vcs.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
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CMakeLists.txt

+cmake_minimum_required(VERSION 3.10)
+
+project(C-Stuff C)
+
+set(CMAKE_C_STANDARD 11)
+
+add_executable(Multithreaded_Search Multithreaded_Search/main.c)
+add_executable(Fork_and_Pipe Fork_and_Pipe/main.c)
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Fork_and_Pipe/main.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+
+int main(int argc, char *argv[]){
+
+    pid_t pid;
+
+    int conditions[2]; // write = 1, read = 0
+    pipe(conditions); // create a pipe
+
+    pid = fork(); // duplicate the process
+
+    if(pid == 0){
+        /*child*/
+        printf("Iam the child\n");
+
+        int qsum = 0;
+        for(int i = 0; i < strlen(argv[1]); i++){
+            qsum += argv[1][i] - '0';
+        }
+
+        close(conditions[0]); // -> child wants to write
+        write(conditions[1], &qsum, sizeof(qsum)); // -> write the qsum to the pipe
+        close(conditions[1]); // -> close the writing
+
+    }
+    else if (pid != -1){
+        /*parent*/
+        printf("Iam the parent\n");
+
+        int qsum = 0;
+        close(conditions[1]);
+        read(conditions[0], &qsum, sizeof(qsum));
+        close(conditions[0]);
+
+        printf("The qsum is: %d\n", qsum);
+    }
+    else {
+        perror("Error while forking");
+        return -1;
+    }
+
+    return 0;
+}
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Multithreaded_Search/main.c

+/***
+ * @author: Marc Feger
+ * @mail: marc.feger@uni-duesseldorf.de
+ */
+#include <stdlib.h>
+#include <time.h>
+#include <printf.h>
+#include <ntsid.h>
+#include <pthread.h>
+
+// SIZE > COUNT_THREADS is a must
+#define SIZE 100000000
+#define COUNT_THREADS 1
+
+struct arguments {
+    int id;
+    int *array;
+    int *max;
+};
+
+typedef struct arguments arguments_s;
+
+int *create_random_array() {
+    srand((unsigned int) time(NULL));
+    int *array = malloc(SIZE * sizeof(int));
+    for (int i = 0; i < SIZE; i++) {
+        array[i] = rand();
+    }
+    return array;
+}
+
+int get_maximum(const int *array, int from, int to) {
+    int max = 0;
+    for (int i = from; i < to; i++) {
+        if (array[i] > max) max = array[i];
+    }
+    return max;
+}
+
+void *worker(void *arg) {
+    arguments_s *args = (arguments_s *) arg;
+
+    int from = args->id * (SIZE / COUNT_THREADS);
+    int to = (args->id + 1) * (SIZE / COUNT_THREADS);
+    if (args->id == COUNT_THREADS - 1) to = SIZE;
+
+    args->max[args->id] = get_maximum(args->array, from, to);
+
+    return NULL;
+}
+
+int main(void) {
+
+    int *array = create_random_array();
+    int *max = malloc(SIZE * sizeof(int));
+
+    arguments_s args;
+
+    args.array = array;
+    args.max = max;
+
+    pthread_t threads[COUNT_THREADS];
+
+    clock_t start_t;
+
+    start_t = clock();
+    // create all threads
+    for (int i = 0; i < COUNT_THREADS; i++) {
+        args.id = i;
+        if (pthread_create(&threads[i], NULL, worker, (void *) &args) != 0) {
+            printf("pthread_create() did not create a thread");
+        }
+        if (pthread_join(threads[i], NULL) != 0) {
+            printf("pthread_join() did not join a thread");
+        }
+    }
+
+
+    int total_max = get_maximum(args.max, 0, COUNT_THREADS);
+    printf("The total maximum is: %d\n", total_max);
+    printf("It took %f clocks for %d threads to find the maximum of %d elements\n",
+           ((double) (start_t - clock())) / CLOCKS_PER_SEC, COUNT_THREADS, SIZE);
+
+    free(array);
+    free(max);
+
+    return 0;
+}
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