プログラミング言語C K&R著の演習問題を解答していく その2

C言語のバイブルと言われる、K&Rの「プログラミング言語C」を第一章から読み進めて演習問題を記録していく。

プログラミング言語C 第2版 ANSI規格準拠

第1章

• 1-10

#include <stdio.h>
int main(){
  int c;
  while((c = getchar()) != EOF){
    if(c == '\t'){
      printf("\\t");
    }else if(c == '\b'){
      printf("\\b");
    }else if(c == '\\'){
      printf("\\\\");
    }else{
      putchar(c);
    }
  }
}

• 1-11

#include <stdio.h>
#define IN  1
#define OUT 0

int main(){
  int wordcounter, nowstatus;
  int c;
  nowstatus = OUT;
  wordcounter = 0;
  while((c = getchar()) != EOF){
    if(c == '\t' || c == ' ' || c == '\n'){
      nowstatus = OUT;
    }else if(nowstatus == OUT){
      nowstatus = IN;
      ++wordcounter;
    }
  }
  printf("%d\n", wordcounter);
}

• 1-12

#include <stdio.h>

#define IN  0
#define OUT 1

int main(){
  int nowstatus = OUT;
  int c;
  while((c = getchar()) != EOF){
    if(c == ' ' || c == '\t' || c == '\n'){
      if(nowstatus == IN){
        printf("\n");
        nowstatus = OUT;
      }
    }else{
      nowstatus = IN;
      putchar(c);
    }
  }
}

• 1-13

#include <stdio.h>

#define IN  0
#define OUT 1
int main(){
  int wordsize[10];
  int c;
  int i,j,k,l;
  int wordstatus;
  wordstatus = OUT;
  i = 0;
  for(j = 0; j < 10; j++){
    wordsize[j] = 0;
  }
  while((c = getchar()) != EOF){
    if(c == ' ' || c == '\t' || c == '\n'){
      if(wordstatus == IN){
        if(i <= 9){
          wordsize[i] += 1;
        }else{
          wordsize[9] += 1;
        }
        wordstatus = OUT;
        i = 0;
      }
    }else{
      wordstatus = IN;
      i += 1;
    }
  }
  for(k = 0; k < 10; k++){
    l = 0;
    if(wordsize[k] != 0){
      printf("%2d:%d",k ,wordsize[k]);
      while( l < wordsize[k]){
        printf("*");
        l += 1;
      }
      printf("\n");
    }
  }
}

• 1-13-2

#include <stdio.h>

#define IN  0
#define OUT 1
int main(){
  int wordsize[10];
  int c;
  int i,j,k,l,m;
  int wordstatus;
  wordstatus = OUT;
  i = 0;
  for(j = 0; j < 10; j++){
    wordsize[j] = 0;
  }

  while((c = getchar()) != EOF){
    if(c == ' ' || c == '\t' || c == '\n'){
      if(wordstatus == IN){
        if(i <= 9){
          wordsize[i] += 1;
        }else{
          wordsize[9] += 1;
        }
        wordstatus = OUT;
        i = 0;
      }
    }else{
      wordstatus = IN;
      i += 1;
    }
  }

  int output[50];
  for(k = 0; k < 50; k++){
    output[k] = 0;
  }

  for(l = 0; l < 10; l++){
    if(wordsize[l] >= 5){
      output[l] = 1;
    }
    if(wordsize[l] >= 4){
      output[10 + l] = 1;
    }
    if(wordsize[l] >= 3){
      output[20 + l] = 1;
    }
    if(wordsize[l] >= 2){
      output[30 + l] = 1;
    }
    if(wordsize[l] >= 1){
      output[40 + l] = 1;
    }
  }

  for(m = 0; m < 50; m++){
    if(output[m] == 1){
      printf("*");
    }else{
      printf(" ");
    }
    if((m % 10) == 9){
      printf("\n");
    }
  }
  printf("0123456789\n");
}

• 1-14

#include <stdio.h>

int main(){
  int ascii[128];
  int c;
  int count;
  int i,j,k;
  for(i = 0; i < 128; ++i){
    ascii[i] = 0;
  }

  while((c = getchar()) != EOF){
    ascii[c] += 1;
  }
  for(j = 0; j< 128; ++j){
    if(ascii[j] > 0){
      count = ascii[j];
      printf("%c:", j);
      for(k = 0; k < count; k++){
        printf("*");
      }
      printf("\n");
    }
  }
}

• 1-15

#include <stdio.h>

float changeunit(float f);

int main(){
  float fahr, selsius;
  int lower, upper, step;

  lower = 0;
  upper = 300;
  step = 20;

  fahr = lower;
  printf("fahr-selsius conversion table\n");
  while(fahr <= upper){
    printf("%3.0f %6.1f\n", fahr, changeunit(fahr));
    fahr += step;
  }
}

float changeunit(float f){
  float v;
  v = ((5.0/9.0) * (f - 32.0));
  return v;
}