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Input widgets allow users to enter and edit data. Dear ImGui provides input functions for text, integers, floats, and other data types.

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Text Input

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InputText()

Single-line text input: 
IMGUI_API bool InputText(const char* label, char* buf, size_t buf_size, 
                         ImGuiInputTextFlags flags = 0, 
                         ImGuiInputTextCallback callback = NULL, 
                         void* user_data = NULL);
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label
const char*
required
Widget label
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buf
char*
required
Character buffer to edit
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buf_size
size_t
required
Size of the buffer (including null terminator)
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flags
ImGuiInputTextFlags
default:"0"
Optional input text flags (see below)
static char text[128] = "Hello, world!";
ImGui::InputText("##input", text, IM_COUNTOF(text));

if (ImGui::IsItemDeactivatedAfterEdit()) {
    // Text was edited and user pressed Enter or clicked away
    printf("Final text: %s\n", text);
}

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InputTextMultiline()

Multi-line text input: 
IMGUI_API bool InputTextMultiline(const char* label, char* buf, size_t buf_size,
                                  const ImVec2& size = ImVec2(0, 0),
                                  ImGuiInputTextFlags flags = 0,
                                  ImGuiInputTextCallback callback = NULL,
                                  void* user_data = NULL);

static char multiline[1024] = "Line 1\nLine 2\nLine 3";
ImGui::InputTextMultiline("##multiline", multiline, IM_COUNTOF(multiline),
                          ImVec2(-FLT_MIN, ImGui::GetTextLineHeight() * 16));

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InputTextWithHint()

Text input with placeholder hint: 
IMGUI_API bool InputTextWithHint(const char* label, const char* hint, 
                                 char* buf, size_t buf_size,
                                 ImGuiInputTextFlags flags = 0,
                                 ImGuiInputTextCallback callback = NULL,
                                 void* user_data = NULL);

static char email[128] = "";
ImGui::InputTextWithHint("##email", "Enter email address", email, IM_COUNTOF(email));

static char search[256] = "";
ImGui::InputTextWithHint("##search", "Search...", search, IM_COUNTOF(search));

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Input Text Flags

Customize text input behavior with flags: 
// Numbers only
ImGui::InputText("##numbers", buf, 128, ImGuiInputTextFlags_CharsDecimal);

// Hexadecimal only
ImGui::InputText("##hex", buf, 128, ImGuiInputTextFlags_CharsHexadecimal);

// No blank characters
ImGui::InputText("##noblank", buf, 128, ImGuiInputTextFlags_CharsNoBlank);

// Uppercase only
ImGui::InputText("##upper", buf, 128, ImGuiInputTextFlags_CharsUppercase);
Common flags include:
  • ImGuiInputTextFlags_EnterReturnsTrue - Return true when Enter pressed
  • ImGuiInputTextFlags_Password - Display as password (***)
  • ImGuiInputTextFlags_ReadOnly - Read-only mode
  • ImGuiInputTextFlags_CharsDecimal - Allow 0-9 . + - *
  • ImGuiInputTextFlags_CharsNoBlank - Filter out spaces and tabs

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Numeric Input

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InputInt()

Integer input with optional step buttons: 
IMGUI_API bool InputInt(const char* label, int* v, int step = 1, int step_fast = 100,
                        ImGuiInputTextFlags flags = 0);

static int i0 = 123;
ImGui::InputInt("input int", &i0);

// With custom steps
static int i1 = 0;
ImGui::InputInt("input int (step)", &i1, 5, 20);

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InputFloat()

Floating-point input: 
IMGUI_API bool InputFloat(const char* label, float* v, 
                          float step = 0.0f, float step_fast = 0.0f,
                          const char* format = "%.3f",
                          ImGuiInputTextFlags flags = 0);

static float f0 = 0.001f;
ImGui::InputFloat("input float", &f0, 0.01f, 1.0f, "%.3f");

// Scientific notation
static float f1 = 1.e10f;
ImGui::InputFloat("input scientific", &f1, 0.0f, 0.0f, "%e");

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InputDouble()

Double-precision input: 
IMGUI_API bool InputDouble(const char* label, double* v,
                           double step = 0.0, double step_fast = 0.0,
                           const char* format = "%.6f",
                           ImGuiInputTextFlags flags = 0);

static double d0 = 999999.00000001;
ImGui::InputDouble("input double", &d0, 0.01, 1.0, "%.8f");

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Multi-Component Input

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InputFloat2/3/4()

Input multiple float values: 
IMGUI_API bool InputFloat2(const char* label, float v[2], const char* format = "%.3f",
                           ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputFloat3(const char* label, float v[3], const char* format = "%.3f",
                           ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputFloat4(const char* label, float v[4], const char* format = "%.3f",
                           ImGuiInputTextFlags flags = 0);

static float vec2[2] = { 0.0f, 0.0f };
static float vec3[3] = { 0.0f, 0.0f, 0.0f };
static float vec4[4] = { 0.10f, 0.20f, 0.30f, 0.44f };

ImGui::InputFloat2("position", vec2);
ImGui::InputFloat3("direction", vec3);
ImGui::InputFloat4("color", vec4);

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InputInt2/3/4()

Input multiple integer values: 
IMGUI_API bool InputInt2(const char* label, int v[2], ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputInt3(const char* label, int v[3], ImGuiInputTextFlags flags = 0);
IMGUI_API bool InputInt4(const char* label, int v[4], ImGuiInputTextFlags flags = 0);

static int ivec3[3] = { 10, 20, 30 };
ImGui::InputInt3("coordinates", ivec3);

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Generic Scalar Input

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InputScalar()

Input any scalar data type: 
IMGUI_API bool InputScalar(const char* label, ImGuiDataType data_type, void* p_data,
                           const void* p_step = NULL, const void* p_step_fast = NULL,
                           const char* format = NULL, ImGuiInputTextFlags flags = 0);
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data_type
ImGuiDataType
required
Data type:
  • ImGuiDataType_S8, ImGuiDataType_U8
  • ImGuiDataType_S16, ImGuiDataType_U16
  • ImGuiDataType_S32, ImGuiDataType_U32
  • ImGuiDataType_S64, ImGuiDataType_U64
  • ImGuiDataType_Float, ImGuiDataType_Double
static ImS8 s8_v = 127;
static ImU8 u8_v = 255;
static ImS16 s16_v = 32767;

ImGui::InputScalar("int8", ImGuiDataType_S8, &s8_v);
ImGui::InputScalar("uint8", ImGuiDataType_U8, &u8_v);
ImGui::InputScalar("int16", ImGuiDataType_S16, &s16_v);

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Input Validation and Callbacks

Use callbacks to validate or process input: 
static int MyCallback(ImGuiInputTextCallbackData* data) {
    if (data->EventFlag == ImGuiInputTextFlags_CallbackCharFilter) {
        // Custom character filtering
        if (data->EventChar < 256 && strchr("0123456789ABCDEFabcdef", (char)data->EventChar)) {
            return 0;  // Accept
        }
        return 1;  // Reject
    }
    return 0;
}

static char hex_input[16] = "";
ImGui::InputText("Hex", hex_input, 16, 
                 ImGuiInputTextFlags_CallbackCharFilter, MyCallback);

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Complete Example

void ShowInputDemo() {
    ImGui::Begin("Input Demo");
    
    // Text input
    static char text[128] = "Hello, world!";
    ImGui::InputText("Name", text, IM_COUNTOF(text));
    
    // Text with hint
    static char email[128] = "";
    ImGui::InputTextWithHint("Email", "user@example.com", email, IM_COUNTOF(email));
    
    // Password
    static char password[128] = "";
    ImGui::InputText("Password", password, IM_COUNTOF(password), 
                     ImGuiInputTextFlags_Password);
    
    ImGui::Spacing();
    
    // Numeric inputs
    static int i0 = 123;
    ImGui::InputInt("Integer", &i0);
    
    static float f0 = 0.001f;
    ImGui::InputFloat("Float", &f0, 0.01f, 1.0f, "%.3f");
    
    static double d0 = 999.999;
    ImGui::InputDouble("Double", &d0, 0.01, 1.0, "%.3f");
    
    ImGui::Spacing();
    
    // Multi-component
    static float vec3[3] = { 0.0f, 3.14159f, 2.71828f };
    ImGui::InputFloat3("Vector", vec3);
    
    ImGui::Spacing();
    
    // Multiline text
    static char multiline[512] = "Line 1\nLine 2\nLine 3";
    ImGui::InputTextMultiline("##multiline", multiline, IM_COUNTOF(multiline),
                              ImVec2(-FLT_MIN, ImGui::GetTextLineHeight() * 8));
    
    ImGui::End();
}

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Best Practices

Use ImGuiInputTextFlags_EnterReturnsTrue to detect when the user presses Enter to confirm input.
Always provide a buffer large enough for your expected input plus the null terminator.
Check IsItemDeactivatedAfterEdit() after an input widget to detect when editing is complete and the value has changed.