finished cls04

report-cls04.tex

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+\documentclass[xelatex,a4paper,11pt,ja=standard]{bxjsarticle}
+
+\usepackage{tex/preamble}
+\usepackage{tex/simple-title}
+
+\reportauthor{柴田健琉}
+\reporttitle{情報処理2 - 前期第4回課題}
+\reportdate{2026年}{05月}{11日}
+\turnindate{2026年}{05月}{12日}
+
+\begin{document}
+    \simpletitle{}
+
+    \section{はじめに}
+
+    この課題のプログラムは以下の環境での動作が確認されている：
+
+    \begin{itemize}
+        \item {OS: NixOS 25.11 Xantusia, Linux 7.0.3 x86\_64}
+        \item {CC: GCC 15.2.0}
+        \item {CFLAGS: \texttt{-g -O1 -Wall -Wpedantic}}
+        \item {ファイルエンコーディング: UTF-8}
+    \end{itemize}
+
+    \section{補助関数郡}
+
+    今回の課題では前期第3回課題で作成した関数を使用する．再利用性を高めるために\texttt{reduce.h}を作成した．
+
+    \lstinputlisting[language=C,title={\texttt{reduce.h}}]{src/cls04/reduce.h}
+
+    また，分数の入出力等に関する関数を\texttt{utils.h}に記述した．
+
+    \lstinputlisting[language=C,title={\texttt{utils.h}}]{src/cls04/utils.h}
+
+    \newpage
+
+    \section{課題1}
+
+    \texttt{reduce}関数を用いて分数どうしの加算を行うプログラム．
+
+    \lstinputlisting[language=C,title={課題1のプログラム}]{src/cls04/a1.c}
+
+    \subsection{実行結果}
+
+    \begin{figure}[tbh]
+        \centering
+        \includegraphics[width=12cm]{assets/cls04-a1.png}
+        \caption{課題1の実行結果}
+    \end{figure}
+
+    \newpage
+
+    \section{課題2}
+
+    \texttt{reduce}関数を用いて分数どうしの減算を行うプログラム．
+
+    \lstinputlisting[language=C,title={課題2のプログラム}]{src/cls04/a2.c}
+
+    \subsection{実行結果}
+
+    \begin{figure}[tbh]
+        \centering
+        \includegraphics[width=12cm]{assets/cls04-a2.png}
+        \caption{課題2の実行結果}
+    \end{figure}
+
+    \newpage
+
+    \section{課題3}
+
+    \texttt{reduce}関数を用いて分数どうしの乗算を行うプログラム．
+
+    \lstinputlisting[language=C,title={課題3のプログラム}]{src/cls04/a3.c}
+
+    \subsection{実行結果}
+
+    \begin{figure}[tbh]
+        \centering
+        \includegraphics[width=12cm]{assets/cls04-a3.png}
+        \caption{課題3の実行結果}
+    \end{figure}
+
+    \newpage
+
+    \section{課題4}
+
+    標準入力から自然数を取得する関数\texttt{getnum}を作成する．
+
+    \lstinputlisting[language=C,title={課題4のプログラム}]{src/cls04/a4.c}
+
+    \subsection{実行結果}
+
+    \begin{figure}[tbh]
+        \centering
+        \includegraphics[width=12cm]{assets/cls04-a4.png}
+        \caption{課題4の実行結果}
+    \end{figure}
+\end{document}

src/cls04/Makefile

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+include ../common.mk
+
+PROJECT_NAME:=cls04
+
+TGTS:=$(patsubst %.c,%,$(wildcard *.c))
+
+all: $(TGTS)
+
+%: %.c
+	@mkdir -p $(BUILD_PATH)/$(PROJECT_NAME)
+	$(CC) $(CFLAGS) -I. $^ -o $(BUILD_PATH)/$(PROJECT_NAME)/$@
+
+clean:
+	$(RM) -drf $(BUILD_PATH)/$(PROJECT_NAME)

src/cls04/a1.c

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+#include <stdio.h>
+
+#include "reduce.h"
+#include "utils.h"
+
+int addFrac(int x[], int y[]) {
+    if (x[1] == 0 || y[1] == 0) {
+        return -1;
+    }
+
+    int l = lcm(x[1], y[1]);
+    int z[] = {
+        (x[0] * l)/x[1] + (y[0] * l)/y[1],
+        l
+    };
+
+    reduce(z);
+    formatNeg(z);
+
+    x[0] = z[0];
+    x[1] = z[1];
+    return 0;
+}
+
+int main(void) {
+    int x[2] = {0};
+    int y[2] = {0};
+
+    inputFrac(x);
+    inputFrac(y);
+
+    int ret = addFrac(x, y);
+
+    if (ret == 0) {
+        printFrac(x);
+        putchar('\n');
+    } else {
+        fprintf(stderr, "Error: detected zero div\n");
+    }
+
+    return 0;
+}

src/cls04/a2.c

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+#include <stdio.h>
+
+#include "reduce.h"
+#include "utils.h"
+
+int subFrac(int x[], int y[]) {
+    if (x[1] == 0 || y[1] == 0) {
+        return -1;
+    }
+
+    int l = lcm(x[1], y[1]);
+    int z[] = {
+        (x[0] * l)/x[1] - (y[0] * l)/y[1],
+        l
+    };
+
+    reduce(z);
+    formatNeg(z);
+
+    x[0] = z[0];
+    x[1] = z[1];
+
+    return 0;
+}
+
+int main(void) {
+    int x[2] = {0};
+    int y[2] = {0};
+
+    inputFrac(x);
+    inputFrac(y);
+
+    int ret = subFrac(x, y);
+
+    if (ret == 0) {
+        printFrac(x);
+        putchar('\n');
+    } else {
+        fprintf(stderr, "Error: detected zero div\n");
+    }
+
+    return 0;
+}

src/cls04/a3.c

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+#include <stdio.h>
+
+#include "reduce.h"
+#include "utils.h"
+
+int mulFrac(int x[], int y[]) {
+    if (x[1]*y[1] == 0) {
+        return -1;
+    }
+
+    int z[] = {
+        x[0] * y[0],
+        x[1] * y[1]
+    };
+
+    reduce(z);
+    formatNeg(z);
+
+    x[0] = z[0];
+    x[1] = z[1];
+
+    return 0;
+}
+
+int main(void) {
+    int x[2] = {0};
+    int y[2] = {0};
+
+    inputFrac(x);
+    inputFrac(y);
+
+    int ret = mulFrac(x, y);
+
+    if (ret == 0) {
+        printFrac(x);
+        putchar('\n');
+    } else {
+        fprintf(stderr, "Error: Detected zero div\n");
+    }
+
+    return 0;
+}

src/cls04/a4.c

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+#include <stdio.h>
+
+int getnum(void) {
+    int ch, n = 0;
+
+    int stack[10] = {0}; // ceil(log_10(2^31))
+    int i = 0;
+    while ((ch = getchar()) != '\n') {
+        int x = ch - '0';
+        if (x < 0 || x > 9) {
+            continue;
+        }
+        if (i <= 9) stack[i++] = x; // stack push
+    }
+
+    int d = 1;
+    for (int j = i - 1; j >= 0; j--) {
+        n += stack[j] * d; // stack pop
+        d = d * 10;
+    }
+
+    return n;
+}
+
+int main(void) {
+    int ret = getnum();
+
+    printf("got: %d\n", ret);
+
+    return 0;
+}

src/cls04/reduce.h

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+#ifndef __REDUCE_H__
+#define __REDUCE_H__
+
+int gcm(int a, int b) {
+    int x = a, y = b;
+    if (x < y) {
+        x = b;
+        y = a;
+    }
+    int r = a % b;
+    if (r == 0) return b;
+    return gcm(b, r);
+}
+
+int lcm(int a, int b) {
+    int g = gcm(a, b);
+    return b * a / g;
+}
+
+void reduce(int x[]) {
+    int a = x[0], b = x[1];
+    int g = gcm(a, b);
+    x[0] = a / g;
+    x[1] = b / g;
+}
+
+
+#endif // __REDUCE_H__

src/cls04/utils.h

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+#ifndef __UTILS_H__
+#define __UTILS_H__
+
+#include <stdio.h>
+
+void inputFrac(int x[]) {
+    printf("Input fraction(a/b): ");
+    scanf("%d/%d", &x[0], &x[1]);
+}
+
+void formatNeg(int x[]) {
+    size_t sz = sizeof(int);
+    int cnt = 0;
+    for (size_t i = 0; i < 2; i++) {
+        cnt += x[i] < 0 ? 1 : 0;
+        x[i] = x[i] < 0 ? x[i] * -1 : x[i];
+    }
+
+    if (cnt == 1)
+        x[0] = -1 * x[0];
+}
+
+void printFrac(int x[]) {
+    if (x[1] == 1) {
+        printf("%d", x[0]);
+    } else {
+        printf("%d/%d", x[0], x[1]);
+    }
+}
+
+#endif // __UTILS_H__