Align columns/C: Difference between revisions

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Latest revision as of 16:23, 1 September 2022

#include <stdio.h>

const char *str = 
	"Given$a$text$file$of$many$lines,$where$fields$within$a$line$\n"
	"are$delineated$by$a$single$'dollar'$character,$write$a$program\n"
	"that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$\n"
	"column$are$separated$by$at$least$one$space.\n"
	"Further,$allow$for$each$word$in$a$column$to$be$either$left$\n"
	"justified,$right$justified,$or$center$justified$within$its$column.";

void align(const char *in, char alignment)
{
	int col, i, l, r;
	int w[1024] = {0};
	const char *s;

	for (s = in, i = col = 0; s[i]; s += i + 1) {
		for (i = 0; s[i] && s[i] != '$' && s[i] != '\n'; i++);

		if (i > w[col]) w[col] = i;

		if (col++ >= 1024) abort(); /* artificial limit */

		if (s[i] == '\n') col = 0;
		if (!s[i]) break;
	}

	for (s = in, i = col = 0; s[i]; s += i + 1) {
		for (i = 0; s[i] && s[i] != '$' && s[i] != '\n'; i++);

		switch(alignment) {
		case 'l':	r = w[col] - i; break;
		case 'c':	r = (w[col] - i)/2; break;
		case 'r':	r = 0; break;
		}
		l = w[col++] - i - r + 1;

		while (l--) putchar(' ');
		printf("%.*s", i, s);
		while (r--) putchar(' ');

		if (s[i] != '$') {
			putchar('\n');
			col = 0;
		}
		if (!s[i]) break;
	}
}

int main(void)
{
	puts("\n----  right ----"); align(str, 'r');
	puts("\n----  left  ----"); align(str, 'l');
	puts("\n---- center ----"); align(str, 'c');
	return 0;
}

@@ Line 1: / Line 1: @@
 {{collection|Column Aligner}}
-<lang c>#include <stdio.h>
+<syntaxhighlight lang="c">#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+const char *str =
-struct linelement {
+	"Given$a$text$file$of$many$lines,$where$fields$within$a$line$\n"
-  char **wordlist;
+	"are$delineated$by$a$single$'dollar'$character,$write$a$program\n"
-  int longest;
+	"that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$\n"
-  struct linelement *next;
+	"column$are$separated$by$at$least$one$space.\n"
-};
+	"Further,$allow$for$each$word$in$a$column$to$be$either$left$\n"
+	"justified,$right$justified,$or$center$justified$within$its$column.";
+void align(const char *in, char alignment)
-typedef struct linelement line_t;
-char *trim(char *s, int *len)
 {
+	int col, i, l, r;
-  char *b;
+	int w[1024] = {0};
-  int l;
+	const char *s;
-  while( (*s == ' ') || (*s == '\t') ) s++;
+	for (s = in, i = col = 0; s[i]; s += i + 1) {
+		for (i = 0; s[i] && s[i] != '$' && s[i] != '\n'; i++);
-  b = s;
-  l = strlen(b);
-  s += l; s--;
-  while( (*s == ' ') || (*s == '\t') ) s--;
-  s++; *s = 0;
-  if ( l > *len ) *len = l;
-  return b;
-}
+		if (i > w[col]) w[col] = i;
-char **split(char *l, int c, int *longest)
-{
-  int howmany, i;
-  char **arr;
-  char *n;
-  if ( (n = strchr(l, 10)) != NULL ) *n = 0;
+		if (col++ >= 1024) abort(); /* artificial limit */
-  if ( (n = strchr(l, 13)) != NULL ) *n = 0;
-  for(howmany=1, i=0; l[i] != 0 ; i++)
+		if (s[i] == '\n') col = 0;
+		if (!s[i]) break;
-    if ( (l[i]==c) && ((i+1) < strlen(l))) howmany++;
+	}
-  arr = malloc(sizeof(char *) * (howmany+1));
-  arr[0] = NULL;
-  if ( arr != NULL ) {
-    n = l;
-    for(i=0; i < howmany; i++) {
-      arr[i] = n;
-      n = strchr(n, c);
-      if ( n == NULL ) { break; }
-      *n = 0; n++;
-      arr[i] = trim(arr[i], longest);
-    }
-  }
-  arr[howmany] = NULL;
-  return arr;
-}
+	for (s = in, i = col = 0; s[i]; s += i + 1) {
+		for (i = 0; s[i] && s[i] != '$' && s[i] != '\n'; i++);
+		switch(alignment) {
-#define MAXLINELEN 1024
+		case 'l':	r = w[col] - i; break;
-#define FILLCHAR ' '
+		case 'c':	r = (w[col] - i)/2; break;
+		case 'r':	r = 0; break;
+		}
+		l = w[col++] - i - r + 1;
+		while (l--) putchar(' ');
-/* decide the alignment */
+		printf("%.*s", i, s);
-enum textalign {
+		while (r--) putchar(' ');
-  LEFT_ALIGNED, RIGHT_ALIGNED, CENTER_ALIGNED
-};
-const int alignment = CENTER_ALIGNED;
+		if (s[i] != '$') {
+			putchar('\n');
+			col = 0;
+		}
+		if (!s[i]) break;
+	}
+}
-int main()
+int main(void)
 {
+	puts("\n----  right ----"); align(str, 'r');
-  char buf[MAXLINELEN];
+	puts("\n----  left  ----"); align(str, 'l');
-  line_t *head, *cur;
+	puts("\n---- center ----"); align(str, 'c');
-  char *lb;
+	return 0;
-  int reallongest, i, len, ipos;
+}</syntaxhighlight>
-  head = malloc(sizeof(line_t));
-  memset(head, 0, sizeof(line_t));
-  /* for each line, split it ($-separated words) */
-  cur = head;
-  while ( fgets(buf, MAXLINELEN, stdin) != NULL ) {
-    lb = malloc(strlen(buf));
-    strncpy(lb, buf, strlen(buf));
-    cur->wordlist = split(lb, '$', &(cur->longest));
-    cur->next = malloc(sizeof(line_t));
-    memset(cur->next, 0, sizeof(line_t));
-    cur = cur->next;
-  }
-  cur->next = NULL; /* last node is a end-marker */
-  /* each line holds the longest word length; find the
-     longest among all lines; this determines the width
-     of all columns */
-  reallongest = head->longest;
-  cur = head;
-  while( cur->next != NULL ) {
-    if ( cur->longest > reallongest )
-      reallongest = cur->longest;
-    cur = cur->next;
-  }
-  reallongest++;
-  buf[reallongest] = 0; /* no bounds check... */
-  /* print the columns */
-  cur = head;
-  while( cur->next != NULL ) {
-    for(i=0; cur->wordlist[i] != NULL; i++) {
-      len = strlen(cur->wordlist[i]);
-      switch(alignment) {
-      case LEFT_ALIGNED:
-	ipos = 0;
-	break;
-      case RIGHT_ALIGNED:
-	ipos = reallongest - len;
-	break;
-      case CENTER_ALIGNED:
-	ipos = (reallongest - len)/2;
-	break;
-      }
-      memset(buf, FILLCHAR, reallongest);
-      memcpy(buf+ipos, cur->wordlist[i], len);
-      printf("%s ", buf);
-    }
-    printf("\n");
-    cur = cur->next;
-  }
-}</lang>