ex 1-6

recursivity/ANSWERS.md

+1. affiche 5 a "l'infini" pas de cond de sortie
+2. appel "infini" se limite a la mémoire (stack overflow)
+3. 9 appels affiche : 1 3 1 5
+

recursivity/Makefile

+cc=gcc
+LIBS=-Wextra -Wall -g -fsanitize=address -fsanitize=leak -lm
+
+test :test.x
+	./test.x
+
+test.x: rec.o test.o
+	$(cc) -o $@ $^ $(LIBS)
+
+test.o: test.c
+	$(cc) -c $^ $(LIBS)
+
+main: main.x
+	./main.x
+
+main.x: rec.o main.c
+	$(cc) -o $@ $^ $(LIBS)
+
+rec.o: rec.c rec.h
+	$(cc) -c $^ $(LIBS)
+
+clean:
+	rm -f *.o *.x *.gch

recursivity/main.c

+#include "rec.h"
+int main(){
+
+    show(10);show(0);show(-5);
+    printf("\n%d\n",sum(10));
+
+
+    return EXIT_SUCCESS;
+}
\ No newline at end of file

recursivity/rec.c

+#include "rec.h"
+
+//1
+void show(int n){
+    if(n<=0){
+        return;
+    }
+    n--;
+    show(n);
+    printf("%d ",n);
+}
+
+//2
+int sum(int x){
+      if(x<=0){
+        return 0;
+    }
+    return x+sum(x-1);
+}
+
+//3
+int sum_arr(int arr[],int size){
+
+    if(size<1){
+        return 0;
+    }
+    size--;
+    return arr[size]+sum_arr(arr, size);
+ }
+
+//4
+int count_digits(int x){
+    if(x/10==0){
+        return 1;
+    }
+    x/=10;
+    return 1+count_digits(x);
+}
+
+//5 
+int sum_digits(int x){
+    if(x/10==0){
+        return x;
+    }
+    int r=x%10;
+    x/=10;
+    return r+sum_digits(x);
+}
+
+//ex6
+bool is_sum_digits(char str[],int index,int len){
+    if(index>=len){
+        return true;
+    }
+    bool same=str[index]==str[len];
+    index++;len--;
+    return same&&is_sum_digits(str,index,len);
+}
+
+//ex7 aie aie aie
\ No newline at end of file

recursivity/rec.h

+#ifndef _REC_H_
+#define _REC_H_
+
+#include <assert.h>
+#include <math.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void show(int n);
+int sum(int x);
+int sum_arr(int arr[],int size);
+int count_digits(int x);
+int sum_digits(int x);
+bool is_sum_digits(char str[],int index,int len);
+
+#endif
\ No newline at end of file

recursivity/test.c

+#include <stdlib.h>
+#include "rec.h"
+
+
+
+int main(){
+    assert(sum(10)==55);
+    int arr[3]={1,5,3};
+    assert(sum_arr(arr, 3));
+    assert(count_digits(1234)==4);
+    assert(sum_digits(8345)==20);
+    assert(is_sum_digits("abba", 0, 3));
+    assert(!is_sum_digits("albuchef", 0, 7));
+
+    printf("\ntest ok\n");
+    return EXIT_SUCCESS;
+
+}
\ No newline at end of file