use malloc and free for dynamic variables

CMakeLists.txt

@@ -24,6 +24,7 @@ set(CMAKE_C_STANDARD_REQUIRED ON)
 
 if(MSVC)
     add_compile_definitions(_CRT_SECURE_NO_WARNINGS)
+    add_compile_options(/Za)
 endif(MSVC)
 
 add_subdirectory(conversions)

misc/demonetization.c

@@ -3,13 +3,17 @@
 //generate notes for an entered amount N.
 
 #include <stdio.h>
+#include <stdlib.h>
 
-int ways(int n, int a[], int k)
+int ways(int n, int *a, int k)
 {
-    if(n<0 || k<0) return 0;
-    if(n == 0) return 1;
-    if(k == 0) return 0;
-    return ways(n, a, k-1) + ways(n-a[k-1], a, k);
+    if (n < 0 || k < 0)
+        return 0;
+    if (n == 0)
+        return 1;
+    if (k == 0)
+        return 0;
+    return ways(n, a, k - 1) + ways(n - a[k - 1], a, k);
 }
 
 int main()
@@ -20,15 +24,15 @@ int main()
 
     printf("Number of coins? ");
     scanf("%d", &m);
-    int coin[m], i;
-    for(i=0; i<m; i++)
+    int *coin = (int *)malloc(m * sizeof(int)), i;
+    for (i = 0; i < m; i++)
     {
         printf("coin? ");
         scanf("%d", &coin[i]);
     }
 
     printf("---- your requests --- \n");
-    while(1)
+    while (1)
     {
         printf("amount? exit(0) ");
         scanf("%d", &n);
@@ -38,5 +42,7 @@ int main()
         }
         printf("%d\n", ways(n, coin, m));
     }
+
+    free(coin);
     return 0;
 }

misc/lexicographic_Permutations.c

@@ -2,52 +2,61 @@
 #include <string.h>
 #include <stdlib.h>
 
-void swap(char* left, char* right){
+void swap(char *left, char *right)
+{
     char temp = *left;
     *left = *right;
     *right = temp;
 }
 
-int compare (const void * a, const void * b){
-    return ( *(char*)a - *(char*)b );
+int compare(const void *a, const void *b)
+{
+    return (*(char *)a - *(char *)b);
 }
 
-void PrintSortedPermutations(char str[])
+void PrintSortedPermutations(char *str)
 {
     int strSize = strlen(str);
     qsort(str, strSize, sizeof(char), compare);
 
     int largerPermFound = 1;
-    do{
+    do
+    {
         // 1. Print permutation
         printf("%s\n", str);
         // 2. Find rightmost char that is smaller than char to its right
         int i;
-        for (i = strSize - 2; i >= 0 && str[i] >= str[i+1]; --i){}
+        for (i = strSize - 2; i >= 0 && str[i] >= str[i + 1]; --i)
+        {
+        }
 
         // if we couldn't find one, we're finished, else we can swap
-        if (i >= 0){
+        if (i >= 0)
+        {
             // 3. find character at index j such that str[j] = min(str[k]) && str[k] > str[i] for all k > i
-            int j = i+1, k;
-            for(k=j; k<strSize && str[k]; k++){
+            int j = i + 1, k;
+            for (k = j; k < strSize && str[k]; k++)
+            {
                 if (str[k] > str[i] && str[k] < str[j])
                     j = k;
             }
             // 3. Swap chars at i and j
             swap(&str[i], &str[j]);
             // 4. Sort string to the right of i
-            qsort(str+i+1, strSize-i-1, sizeof(char), compare);
+            qsort(str + i + 1, strSize - i - 1, sizeof(char), compare);
         }
-        else    largerPermFound = 0;
-    }
-    while(largerPermFound);
+        else
+            largerPermFound = 0;
+    } while (largerPermFound);
 }
 
-int main() {
+int main()
+{
     int n; //size of string
-    scanf("%d\n",&n);
-    char str[n];
-    scanf("%s",str);
+    scanf("%d\n", &n);
+    char *str = (char *)malloc(n * sizeof(char));
+    scanf("%s", str);
     PrintSortedPermutations(str);
+    free(str);
     return 0;
 }

misc/sudoku_solver.c

@@ -8,70 +8,86 @@
 
 #include <stdio.h>
 
-const int M=144;
+#define M 144
 int N, R, C;
 
-int OKrow(int a[M], int x, int y, int v) {
+int OKrow(int a[M], int x, int y, int v)
+{
 	int j;
-	for(j=0; j<N; j++)
-		if(a[x*N+j] == v)
+	for (j = 0; j < N; j++)
+		if (a[x * N + j] == v)
 			return 0;
 	return 1;
 }
-int OKcol(int a[M], int x, int y, int v) {
+int OKcol(int a[M], int x, int y, int v)
+{
 	int i;
-	for(i=0; i<N; i++)
-		if(a[i*N+y] == v)
+	for (i = 0; i < N; i++)
+		if (a[i * N + y] == v)
 			return 0;
 	return 1;
 }
-int OKbox(int a[M], int x, int y, int v) {
-	int bi=x/R, bj=y/C, i, j;
-	for(i=0; i<R; i++)
-		for(j=0; j<C; j++)
-			if(a[(i + bi*R)*N + (j + bj*C)] == v)
+int OKbox(int a[M], int x, int y, int v)
+{
+	int bi = x / R, bj = y / C, i, j;
+	for (i = 0; i < R; i++)
+		for (j = 0; j < C; j++)
+			if (a[(i + bi * R) * N + (j + bj * C)] == v)
 				return 0;
 	return 1;
 }
-int OK(int a[M], int x, int y, int v) {
-	return OKrow(a,x,y,v) && OKcol(a,x,y,v) && OKbox(a,x,y,v);
+int OK(int a[M], int x, int y, int v)
+{
+	return OKrow(a, x, y, v) && OKcol(a, x, y, v) && OKbox(a, x, y, v);
 }
 
-void print(int a[M]) {
+void print(int a[M])
+{
 	int i, j;
-	for(i=0; i<N; i++)
-		for(j=0; j<N; j++)
-			printf("%d%c", a[i*N+j], (j==N-1 ? '\n':' '));
+	for (i = 0; i < N; i++)
+		for (j = 0; j < N; j++)
+			printf("%d%c", a[i * N + j], (j == N - 1 ? '\n' : ' '));
 }
 
-int solve(int a[M]) {
-	int i, j, v, rem=0;
-	for(i=0; i<N; i++) {
-		for(j=0; j<N; j++) {
-			if(a[i*N+j] == 0) {
+int solve(int a[M])
+{
+	int i, j, v, rem = 0;
+	for (i = 0; i < N; i++)
+	{
+		for (j = 0; j < N; j++)
+		{
+			if (a[i * N + j] == 0)
+			{
 				rem = 1;
-				for(v=1; v<=N; v++) {
-					if(OK(a,i,j,v)) {
-						a[i*N+j] = v;
-						if(solve(a)) return 1;
-						a[i*N+j] = 0;
+				for (v = 1; v <= N; v++)
+				{
+					if (OK(a, i, j, v))
+					{
+						a[i * N + j] = v;
+						if (solve(a))
+							return 1;
+						a[i * N + j] = 0;
 					}
 				}
 			}
 		}
 	}
-	if(rem == 0) return 1;
+	if (rem == 0)
+		return 1;
 	return 0;
 }
 
-int main() {
+int main()
+{
 	scanf("%d%d%d", &N, &R, &C);
 	int a[M], i, j;
-	for(i=0; i<N; i++)
-		for(j=0; j<N; j++)
-			scanf("%d", &a[i*N+j]);
+	for (i = 0; i < N; i++)
+		for (j = 0; j < N; j++)
+			scanf("%d", &a[i * N + j]);
 
-	if(solve(a)) print(a);
-	else printf("Invalid\n");
+	if (solve(a))
+		print(a);
+	else
+		printf("Invalid\n");
 	return 0;
 }

numerical_methods/durand_kerner_roots.c

@@ -22,7 +22,7 @@
 /**
  * define polynomial function
  **/
-long double complex function(double *coeffs, unsigned int degree, long double complex x)
+long double complex poly_function(double *coeffs, unsigned int degree, long double complex x)
 {
     long double complex out = 0.;
     unsigned int n;
@@ -154,7 +154,7 @@ int main(int argc, char **argv)
 
         for (n = 0; n < degree - 1; n++)
         {
-            long double complex numerator = function(coeffs, degree, s0[n]);
+            long double complex numerator = poly_function(coeffs, degree, s0[n]);
             long double complex denominator = 1.0;
             for (i = 0; i < degree - 1; i++)
                 if (i != n)