done

programs/p413/info.json

@@ -0,0 +1,10 @@
+{
+  "language": "C",
+  "name": "演習 4-13",
+  "description": "1から$n$までの総和を求めるプログラム。",
+  "output": {
+    "type": "screenshot",
+    "content": "./assets/p413.png"
+  },
+  "note": ""
+}

programs/p413/main.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+int main(void) {
+    int n;
+    int sum = 0;
+
+numInput:
+    printf("Input integer: ");
+    scanf("%d", &n);
+
+    if (n < 1) {
+        puts("Error: Please type in non-zero positive integer.");
+        goto numInput;
+    }
+
+    for (int i = 1; i <= n; i++) {
+        sum += i;
+    }
+
+    printf("ANS: %d", sum);
+
+    return 0;
+}

programs/p414/info.json

@@ -0,0 +1,10 @@
+{
+  "language": "C",
+  "name": "演習 4-14",
+  "description": "1,2,3...8,9,0を入力した整数値個表示するプログラム。",
+  "output": {
+    "type": "screenshot",
+    "content": "./assets/p414.png"
+  },
+  "note": ""
+}

programs/p414/main.c

@@ -0,0 +1,22 @@
+#include <stdio.h>
+
+int main(void) {
+    int n;
+
+numInput:
+    printf("Input positive integer: ");
+    scanf("%d", &n);
+
+    if (n < 0) {
+        puts("Please input positive integer.");
+        goto numInput;
+    }
+
+    for (int i = 1; i <= n; i++) {
+        printf("%d", i % 10);
+    }
+
+    putchar('\n');
+
+    return 0;
+}

programs/p418/info.json

@@ -0,0 +1,10 @@
+{
+  "language": "C",
+  "name": "演習 4-18",
+  "description": "入力した整数値の個数分アスタリスクを各行に5個ずつ表示するプログラム。",
+  "output": {
+    "type": "screenshot",
+    "content": "./assets/p418.png"
+  },
+  "note": ""
+}

programs/p418/main.c

@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+#define CHARSPERLINE 5
+
+int main(void) {
+    int n;
+
+numInput:
+    printf("Input integer: ");
+    scanf("%d", &n);
+
+    if (n < 1) {
+        puts("Please input non-zero positive integer.");
+        goto numInput;
+    }
+
+    for (int i = 1; i <= n; i++) {
+        putchar('*');
+        if (i % CHARSPERLINE == 0) {
+            putchar('\n');
+        }
+    }
+
+    return 0;
+}

programs/p419/info.json

@@ -0,0 +1,10 @@
+{
+  "language": "C",
+  "name": "演習 4-19",
+  "description": "入力した整数値の全約数とその個数を表示するプログラム。",
+  "output": {
+    "type": "screenshot",
+    "content": "./assets/p419.png"
+  },
+  "note": ""
+}

programs/p419/main.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+int main(void) {
+    int n;
+    int factors = 0;
+
+numInput:
+    printf("Input integer: ");
+    scanf("%d", &n);
+
+    if (n < 1) {
+        puts("Please input positive integer.");
+        goto numInput;
+    }
+
+    for (int i = 1; i <= n; i++) {
+        if (n % i == 0) {
+            printf("%d\n", i);
+            factors++;
+        }
+    }
+
+    printf("Number of factors: %d\n", factors);
+
+    return 0;
+}