From ded2940768463382f865524791755f7780a086a1 Mon Sep 17 00:00:00 2001
From: Hojun Choi <hojuchoi@student.42seoul.kr>
Date: Mon, 2 Sep 2024 17:41:19 +0900
Subject: [PATCH] (+ "123" "456")

---
 eval.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/eval.c b/eval.c
index 874242e..b6ee19b 100644
--- a/eval.c
+++ b/eval.c
@@ -120,10 +120,10 @@ fncons(Object *env, Object *list)
 }
 
 Object*
-fnplus(Object *env, Object *list)
+plusint(Object *env, Object *p)
 {
 	long sum = 0;
-	for(Object *p=evallist(env, list); p!=&Nil; p=p->cdr){
+    for(;p!=&Nil; p=p->cdr){
 		if(p->car->type != OINT)
 			error("+ take only number");
 		sum += p->car->num;
@@ -131,6 +131,29 @@ fnplus(Object *env, Object *list)
 	return newint(gc, sum);
 }
 
+Object*
+plusstr(Object *env, Object *p)
+{
+    Object *str = newstr(gc, 16);
+    for(;p!=&Nil; p=p->cdr){
+		if(p->car->type != OSTRING)
+			error("+ take only number");
+        strputs(str, p->car->beg);
+	}
+    return str;
+}
+
+Object*
+fnplus(Object *env, Object *list)
+{
+    Object *p=evallist(env, list);
+    switch(p->car->type){
+    default: error("+ take only [STRING, INT]");
+    case OSTRING: return plusstr(env ,p);
+    case OINT: return plusint(env, p);
+    }
+}
+
 static Object*
 evallist(Object *env, Object *list)
 {