5.1

1 files changed, 53 insertions, 0 deletions

diff --git a/5/1.c b/5/1.c
new file mode 100644
index 0000000..19e4bf2
--- /dev/null
+++ b/5/1.c
@@ -0,0 +1,53 @@
+#include <ctype.h>
+#include <stdio.h>
+
+#define BUFSIZE 100
+
+int getint(int *);
+
+int main(int argc, char *argv[]) {
+  int rc, n;
+
+  while ((rc = getint(&n)) != EOF && rc != 0)
+    printf("\t%d\n", n);
+
+  return 0;
+}
+
+char buf[BUFSIZE];
+int bufp = 0;
+
+int getch() { return (bufp > 0) ? buf[--bufp] : getchar(); }
+
+void ungetch(int c) {
+  if (bufp >= BUFSIZE)
+    printf("ungetch: too many characters\n");
+  else
+    buf[bufp++] = c;
+}
+
+int getint(int *pn) {
+  int c, sign;
+
+  while (isspace(c = getch()))
+    ;
+
+  if (!isdigit(c) && c != EOF && c != '+' && c != '-') {
+    ungetch(c);
+    return 0;
+  }
+
+  sign = (c == '-') ? -1 : 1;
+
+  if (c == '+' || c == '-')
+    c = getch();
+
+  for (*pn = 0; isdigit(c); c = getch())
+    *pn = 10 * *pn + (c - '0');
+  *pn *= sign;
+
+  if (c != EOF)
+    ungetch(c);
+
+  return c;
+}
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