[ios.fmtflags]

# 31 Input/output library [[input.output]](./#input.output)

## 31.5 Iostreams base classes [[iostreams.base]](iostreams.base#ios.fmtflags)

### 31.5.2 Class ios_base [[ios.base]](ios.base#ios.fmtflags)

#### 31.5.2.2 Types [[ios.types]](ios.types#ios.fmtflags)

#### 31.5.2.2.2 Type ios_base​::​fmtflags [ios.fmtflags]

[ð](#lib:fmtflags,ios_base)

`using fmtflags = T1;
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L976)

The typefmtflags is a bitmask type ([[bitmask.types]](bitmask.types "16.3.3.3.3 Bitmask types"))[.](#1.sentence-1)

Setting its elements has the effects indicated in Table [136](#tab:ios.fmtflags "Table 136: fmtflags effects")[.](#1.sentence-2)

Table [136](#tab:ios.fmtflags) — fmtflags effects [[tab:ios.fmtflags]](./tab:ios.fmtflags)  

| [ð](#tab:ios.fmtflags-row-1)<br>**Element** | **Effect(s) if set** |
| --- | --- |
| [ð](#tab:ios.fmtflags-row-2)<br>boolalpha | insert and extract bool type in alphabetic format |
| [ð](#tab:ios.fmtflags-row-3)<br>dec | converts integer input or generates integer output in decimal base |
| [ð](#tab:ios.fmtflags-row-4)<br>fixed | generate floating-point output in fixed-point notation |
| [ð](#tab:ios.fmtflags-row-5)<br>hex | converts integer input or generates integer output in hexadecimal base |
| [ð](#tab:ios.fmtflags-row-6)<br>internal | adds fill characters at a designated internal point in certain generated output,  or identical to right if no such point is designated |
| [ð](#tab:ios.fmtflags-row-7)<br>left | adds fill characters on the right (final positions) of certain generated output |
| [ð](#tab:ios.fmtflags-row-8)<br>oct | converts integer input or generates integer output in octal base |
| [ð](#tab:ios.fmtflags-row-9)<br>right | adds fill characters on the left (initial positions) of certain generated output |
| [ð](#tab:ios.fmtflags-row-10)<br>scientific | generates floating-point output in scientific notation |
| [ð](#tab:ios.fmtflags-row-11)<br>showbase | generates a prefix indicating the numeric base of generated integer output |
| [ð](#tab:ios.fmtflags-row-12)<br>showpoint | generates a decimal-point character unconditionally in generated floating-point output |
| [ð](#tab:ios.fmtflags-row-13)<br>showpos | generates a + sign in non-negative generated numeric output |
| [ð](#tab:ios.fmtflags-row-14)<br>skipws | skips leading whitespace before certain input operations |
| [ð](#tab:ios.fmtflags-row-15)<br>unitbuf | flushes output after each output operation |
| [ð](#tab:ios.fmtflags-row-16)<br>uppercase | replaces certain lowercase letters with their uppercase equivalents in generated output |

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L1016)

Typefmtflags also defines the constants indicated in Table [137](#tab:ios.fmtflags.const "Table 137: fmtflags constants")[.](#2.sentence-1)

Table [137](#tab:ios.fmtflags.const) — fmtflags constants [[tab:ios.fmtflags.const]](./tab:ios.fmtflags.const)  

| [ð](#tab:ios.fmtflags.const-row-1)<br>**Constant** | **Allowable values** |
| --- | --- |
| [ð](#tab:ios.fmtflags.const-row-2)<br>adjustfield | left | right | internal |
| [ð](#tab:ios.fmtflags.const-row-3)<br>basefield | dec | oct | hex |
| [ð](#tab:ios.fmtflags.const-row-4)<br>floatfield | scientific | fixed |
