From abd8710841222b6bfb41133eb20e277777e06438 Mon Sep 17 00:00:00 2001
From: bumbread <thebumboni@gmail.com>
Date: Sat, 6 Aug 2022 11:06:03 +1100
Subject: [PATCH] Fix some printf bugs and document other

---
 src/fmt/gen_fmt.h |  4 ++--
 test/math.c       | 10 +++++-----
 todo              |  2 ++
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/fmt/gen_fmt.h b/src/fmt/gen_fmt.h
index e8362d2..d47edc4 100644
--- a/src/fmt/gen_fmt.h
+++ b/src/fmt/gen_fmt.h
@@ -773,8 +773,8 @@ static inline int pfx(_dtoa)(
     // Print decimal point
     if(decimal_point_n) out('.');
     // Print fractional part that's made out of digits
-    int prec_digs = prec - mant_digits_n;
-    while(mant_digits_n) {
+    int prec_digs = prec < mant_digits_n ? prec : mant_digits_n;
+    while(mant_digits_n < prec_digs) {
         if(-exp >= mant_digits_n) {
             out('0');
         }
diff --git a/test/math.c b/test/math.c
index a1ee11a..0e58bcc 100644
--- a/test/math.c
+++ b/test/math.c
@@ -106,15 +106,15 @@ int main() {
     if(fetestexcept(FE_INVALID)) printf("    FE_INVALID was raised\n");
 
     printf("\n\n=== exp === \n");
-    printf("exp(1) = %f\n", exp(1));
-    printf("FV of $100, continuously compounded at 3%% for 1 year = %f\n",
+    printf("exp(1) = %e\n", exp(1));
+    printf("FV of $100, continuously compounded at 3%% for 1 year = %e\n",
             100*exp(0.03));
     // special values
-    printf("exp(-0) = %f\n", exp(-0.0));
-    printf("exp(-Inf) = %f\n", exp(-INFINITY));
+    printf("exp(-0) = %e\n", exp(-0.0));
+    printf("exp(-Inf) = %e\n", exp(-INFINITY));
     //error handling
     errno = 0; feclearexcept(FE_ALL_EXCEPT);
-    printf("exp(710) = %f\n", exp(710));
+    printf("exp(710) = %e\n", exp(710));
     if(errno == ERANGE) printf("    errno == ERANGE\n");
     if(fetestexcept(FE_OVERFLOW)) printf("    FE_OVERFLOW raised\n");
 
diff --git a/todo b/todo
index 00e019c..dc5a6e9 100644
--- a/todo
+++ b/todo
@@ -48,6 +48,8 @@ stdio.h:
 *   tmpnam
 *   tmpfile_s
 *   tmpnam_s
+*   Printing 8.98846567431157854073e+307
+*   Printing negative zero
 
 stdlib.h:
 *   Strtod base 16 must be correctly rounded