プログラマ専用SNS ミクプラ

#include <stdlib.h>
#include <stdio.h>
int main(void)
{
	char *str;
	int ch,n;
	str=(char *)calloc(6,sizeof(char));//ナル文字分を含む
	n=0;
	while((ch=fgetc(stdin))!=EOF){
		str[n]=ch;
		n++;
		if(n % 5 ==0)
			str=(char *)realloc(str,sizeof(char)*5);
	}
	str[n]='\0';
	puts(str);
	free(str);
	return 0;
}

#include  <stdio.h>
#include  <time.h>
#include  <stdlib.h>

#define   MAX_SIZE (size_t)(1UL << 24)

size_t increment (size_t size)
{
  return size + 1;
}

size_t times2 (size_t size)
{
  return size * 2;
}

clock_t measure (size_t max_size, size_t (*func)(size_t))
{
  clock_t start, end;
  void * ptr;
  size_t size;

  start = clock();
  ptr = 0;
  for (size = 1; size < max_size; size = func(size)) {
    void * nptr = realloc(ptr, size);
    if (nptr == 0) {
      fprintf(stderr, "memory allocation error.\n");
      free(ptr);
      exit(EXIT_FAILURE);
    }
    ptr = nptr;
  }
  free(ptr);
  end = clock();

  return end - start;
}

int main (void)
{
  clock_t first, second;

  first = measure(MAX_SIZE, increment);
  second = measure(MAX_SIZE, times2);

  printf("time1 : %f\n", first / (double)CLOCKS_PER_SEC);
  printf("time2 : %f\n", second / (double)CLOCKS_PER_SEC);

  return EXIT_SUCCESS;
}

１行あたりの文字数に制限があってよいならば、こんな方法があるかもしれません。


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define LEN (80)

int main(void)
{
    char **p, s[LEN];
    int n, i;

    for (p = NULL, n = 0; printf("文字列 > "), fgets(s, sizeof(s), stdin); n++) {
        s[strlen(s)-1] = '\0';
        p = (char **) realloc(p, sizeof(char *) * (n + 1));
        if (!p) {
            exit(1);
        }
        p[n] = (char *) malloc(sizeof(char) * (strlen(s) + 1));
        if (!p[n]) {
            exit(1);
        }
        strcpy(p[n], s);
    }

    for (i = 0; i < n; i++) {
        printf("%s\n", p);
    }

    for (i = 0; i < n; i++) {
        free(p);
    }
    free(p);
    return 0;
}

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
extern void table();
int main(void)
{
    int i_i,count=0;
    char moji[50];
    char *c1;

    printf("*** input moji (but 50 made)...\n");

    while(1){
        gets(moji);
        if ( moji[0] == 'e' ) {
            break;
        }
        table(&c1, moji, &count);
    }

    printf("***** moji list *****\n");
    for(i_i=0; i_i<count; i_i++ ) {
        printf("%s\n",c1[i_i]);
    }
    return 0;
}

void table(char **c1, char *moji, int *count)
{
    if ( *count == 0 ) {
        c1 = (char **)malloc(sizeof(char *));
    } else {
        c1 = (char **)realloc(c1,sizeof(char *)*((*count)+1));
    }

    strcpy(c1[*count], moji);
    (*count)++;
}

char **c1 = NULL;

c1 = table(c1, moji, &count);

char** table(char **c1, char *moji, int *count)
{
    c1 = (char **)realloc(c1,sizeof(char *)*((*count)+1));
    if (c1)
    {
        c1[*count] = (char *)malloc(strlen(moji) + 1);
        strcpy(c1[*count], moji);
        (*count)++;
    }
    return c1;
}

動的確保した領域の後始末を含めて…


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define LEN (80)

char **makeTable(char **p, int *n)
{
    char s[LEN];

    for (p = NULL, *n = 0; printf("文字列 > "), fgets(s, sizeof(s), stdin); (*n)++) {
        s[strlen(s)-1] = '\0';
        p = (char **) realloc(p, sizeof(char *) * (*n + 1));
        if (!p)
            return NULL;
        p[*n] = (char *) malloc(sizeof(char) * (strlen(s) + 1));
        if (!p[*n])
            return NULL;
        strcpy(p[*n], s);
    }
    return p;
}

void printTable(char **p, int n)
{
    int i;

    for (i = 0; i < n; i++)
        printf("%s\n", p);
}

void freeTable(char **p, int n)
{
    while (--n >= 0)
        free(p[n]);
    free(p);
}

int main(void)
{
    char **p;
    int n;

    if (!(p = makeTable(p, &n)))
        exit(1);
    printTable(p, n);
    freeTable(p, n);
    return 0;
}

void table(char ***c1, char *moji, int *count)
{
    *c1 = (char **)realloc(*c1,sizeof(char *)*((*count)+1));
    if (*c1 == NULL) return;
    (*c1)[*count] = (char *)malloc(strlen(moji) + 1);
    if ((*c1)[*count] == NULL) return;
    strcpy((*c1)[*count], moji);
    (*count)++;
}